[CI] Migrate to GHA

# Motivation

We want to modernize our CI.

# Modification

This PR migrates to GH actions and turns on all the right flags.

# Result

Modern CI.

.github/release.yml

@@ -0,0 +1,14 @@
+changelog:
+  categories:
+    - title: SemVer Major
+      labels:
+        - ⚠️ semver/major
+    - title: SemVer Minor
+      labels:
+        - semver/minor
+    - title: SemVer Patch
+      labels:
+        - semver/patch
+    - title: Other Changes
+      labels:
+        - semver/none

.github/workflows/main.yml

@@ -0,0 +1,28 @@
+name: Main
+
+on:
+  push:
+    branches: [main]
+  schedule:
+    - cron: "0 8,20 * * *"
+
+jobs:
+  unit-tests:
+    name: Unit tests
+    uses: apple/swift-nio/.github/workflows/unit_tests.yml@main
+    with:
+      linux_5_9_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error"
+      linux_5_10_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error"
+      linux_6_0_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+      linux_nightly_6_0_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+      linux_nightly_main_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+      windows_6_0_enabled: true
+      windows_nightly_6_0_enabled: true
+      windows_nightly_main_enabled: true
+      windows_6_0_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+      windows_nightly_6_0_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+      windows_nightly_main_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+
+  cxx-interop:
+    name: Cxx interop
+    uses: apple/swift-nio/.github/workflows/cxx_interop.yml@main

.github/workflows/pull_request.yml

@@ -0,0 +1,33 @@
+name: PR
+
+on:
+  pull_request:
+    types: [opened, reopened, synchronize]
+
+jobs:
+  soundness:
+    name: Soundness
+    uses: swiftlang/github-workflows/.github/workflows/soundness.yml@main
+    with:
+      license_header_check_project_name: "SwiftCrypto"
+      format_check_enabled: false
+
+  unit-tests:
+    name: Unit tests
+    uses: apple/swift-nio/.github/workflows/unit_tests.yml@main
+    with:
+      linux_5_9_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error"
+      linux_5_10_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error"
+      linux_6_0_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+      linux_nightly_6_0_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+      linux_nightly_main_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+      windows_6_0_enabled: true
+      windows_nightly_6_0_enabled: true
+      windows_nightly_main_enabled: true
+      windows_6_0_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+      windows_nightly_6_0_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+      windows_nightly_main_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+
+  cxx-interop:
+    name: Cxx interop
+    uses: apple/swift-nio/.github/workflows/cxx_interop.yml@main

.github/workflows/pull_request_label.yml

@@ -0,0 +1,18 @@
+name: PR label
+
+on:
+  pull_request:
+    types: [labeled, unlabeled, opened, reopened, synchronize]
+
+jobs:
+  semver-label-check:
+    name: Semantic Version label check
+    runs-on: ubuntu-latest
+    timeout-minutes: 1
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Check for Semantic Version label
+        uses: apple/swift-nio/.github/actions/pull_request_semver_label_checker@main

.licenseignore

@@ -0,0 +1,42 @@
+.gitignore
+**/.gitignore
+.licenseignore
+.unacceptablelanguageignore
+.gitattributes
+.git-blame-ignore-revs
+.mailfilter
+.mailmap
+.spi.yml
+.swift-format
+.editorconfig
+.github/*
+*.md
+*.txt
+*.yml
+*.yaml
+*.json
+Package.swift
+**/Package.swift
+Package@-*.swift
+**/Package@-*.swift
+Package.resolved
+**/Package.resolved
+Makefile
+*.modulemap
+**/*.modulemap
+**/*.docc/*
+*.xcprivacy
+**/*.xcprivacy
+*.symlink
+**/*.symlink
+Dockerfile
+**/Dockerfile
+Snippets/*
+dev/git.commit.template
+dev/update-benchmark-thresholds
+*.crt
+**/*.crt
+*.pem
+**/*.pem
+*.der
+**/*.der