Config v6

[adams85]

Implements config v6 support.

Features/improvements:

• Fetch new config json version (config_v6.json) and update config model
• SDK key format validation (when client is not set up to use local-only flag overrides)
• AND conditions
• New condition types
  • Prerequisite flag condition
  • Segment condition
• Changed comparison operators
  • (NOT) CONTAINS ANY OF
• New comparison operators
  • BEFORE/AFTER
  • TEXT (NOT) EQUALS (both hashed and cleartext)
  • TEXT (NOT) STARTS/ENDS WITH ANY OF (both hashed and cleartext)
  • ARRAY CONTAINS ANY OF (both hashed and cleartext)
• Percentage options within targeting rules
• Percentage options based on custom attributes
• Custom User Object attribute handling (don't force string values + autoconversions under the hood)
• User Object attribute/comparison value trimming
• Comparison value hashing changes (SHA256, salting)
• Flag overrides vs. config json salt and segments
• EvaluationDetails.matchedTargetingRule/matchedPercentageOption properties (rename + set combinations correctly)
• Update ConfigCatClient.getKeyAndValue

Tests:

• Update cache key/payload tests
• Evaluation matrix tests
  • Config v1 features (both V1 & V2)
  • Config v2 features
• Evaluation log tests
• SDK key format validation
• Custom User Object attribute handling (don't force string values + autoconversions under the hood)
• Flag overrides vs. prerequisite flags (circular dependency, comparison value type mismatch, dependent/prereq flag overriding)
• Flag overrides vs. config json salt and segments
• EvaluationDetails.matchedTargetingRule/matchedPercentageOption properties (rename + set combinations correctly)
• Special character tests (https://trello.com/c/qh4jHrvm)
• Comparison attribute and comparison value trimming tests (https://trello.com/c/vt8FFrSZ)
• Comparison attribute conversion to canonical string representation tests (https://trello.com/c/CZgGrrcb)

Related improvements/fixes:

• Dynamically typed languages should log a warning when default value doesn't match the setting type (see https://trello.com/c/Le6vimGu)
• We should go to the cache in all polling modes instead of using the in memory variable (see https://trello.com/c/rreKm64A)
• Improve message of log event 1103 (https://trello.com/c/Mb7rvm64)

Additional improvements:

• Improve getValueDetails API (see breaking changes). Also, add the getValueDetails counterpart of the getValue overload that doesn't require a default value.
• Handle unexpected errors in the forceRefresh and the evaluation methods (getValue, etc.) to stop potential unhandled exceptions thrown by the evaluation logic from bringing down the consumer's application.
• Return information about the success of the operation (RefreshResult) from the forceRefresh method.
• Add exception message to the log format of the default logger.
• When evaluation fails and there is a related exception, also expose it in EvaluationDetails via the new errorException field. Also, expose the exception to the onError hook callbacks.
• When forceRefresh fails and there is a related exception, also expose it in RefreshResult via the new errorException field.

Additional bugfixes:

• Correct the config service logic to return the error message in case config fetching fails.

Breaking changes:

• Change the return type of ConfigCatClient::get from C pointer to shared_ptr to prevent use after free issues.
• Change the type of the user parameter of evaluation methods (getValue & co.) from C pointer to shared_ptr. Also, change the type of the EvaluationDetails.user field to shared_ptr to prevent use after free issues.
• Change the type of the ConfigCatUser.user field from std::unordered_map<std::string, std::string> to std::unordered_map<std::string, ConfigCatUser::AttributeValue> to allow other values than std::string.
• Make EvaluationDetails generic and change the return type of getValueDetails overloads to return specialized EvaluationDetails objects that contain a value of the same type as the default value.
• Change the return type of getValue(const std::string&, const ConfigCatUser*) and getKeyAndValue from std::shared_ptr to std::optional (for consistency and to remove unnecessary heap allocation).
• Add an extra parameter of type std::exception_ptr to the onError hook callback.
• Make Settings const in the parameter of the onConfigChanged hook callback as it is not supposed to be modified by consumers.
• Rename the error field to errorMessage in EvaluationDetails (and also make it optional).
• Rename the matchedEvaluationRule field to matchedTargetingRule and the matchedEvaluationPercentageRule field to matchedPercentageOption in EvaluationDetails.
• Make the EvaluationDetails.variationId field optional.
• Rework config model (Config and related structs/enums).
• Pass the potential exception as an optional parameter to the ILogger.log method.
• Remove the ConfigCatLogger, ConfigEntry and SettingResult types from the public API.
• Add an abstract getBehavior method to the OverrideDataSource class.
• Use int32_t instead of int for integer setting values for better portability (on most platforms int32_t is just an alias of int).

Requirement checklist (only if applicable)

• I have covered the applied changes with automated tests.
• I have executed the full automated test set against my changes.
• I have validated my changes against all supported platform versions.
• I have read and accepted the contribution agreement.