Add a Vale spelling rule

Closes #46191

This change adds a Vale spelling rule that replaces the current cspell
workflow. The Vale spelling rule ignores spelling errors in code-style
text by default, and includes more configuration options for filtering
spelling errors. This also allows us to reduce the number of linting
workflows.

This change also adds a file containing words to ignore in the
spellcheck rule, based on the current `cspell.json`.

While this change introduces new spelling errors, we can remove these
incrementally, since the Vale spellchecker only flags issues in files
changed by a PR.

This change also configures the Vale spellcheck rule to ignore
abbreviations.

For consistency with the cspell configuration, this change ignores
spelling errors in Terraform and Kubernetes operator reference pages. To
do so, it adds the `{/* vale spelling.spelling = OFF */}` comment
directive in relevant auto-generated reference pages.

.github/workflows/doc-tests.yaml

@@ -101,10 +101,6 @@ jobs:
           cat <<< "$(jq '.scripts."git-update" = "echo Skipping submodule update"' package.json)" > package.json
           yarn build-node
 
-      - name: Check spelling
-        working-directory: 'docs'
-        run: yarn spellcheck content/teleport
-
       - name: Lint docs formatting
         working-directory: 'docs'
         run: yarn markdown-lint
@@ -129,7 +125,7 @@ jobs:
       - name: Run the linter
         uses: errata-ai/vale-action@d89dee975228ae261d22c15adcd03578634d429c # v2.1.1
         with:
-          version: 2.30.0
+          version: 3.8.0
           # Take the comma-separated list of files returned by the "Check for
           # relevant changes" job.
           separator: ","

docs/.vale.ini

@@ -5,4 +5,7 @@ MinAlertLevel = suggestion
 mdx = md
 
 [*.md]
-BasedOnStyles = messaging,examples,3rd-party-products,structure
+BasedOnStyles = messaging,examples,3rd-party-products,structure,spelling
+# Allow ignoring vale style rules in MDX comments
+CommentDelimiters = '{/*,*/}'
+