feat: Create a GitHub action to validate test coverage/compliance with the spec for SDK repos

[JamieSinn]

This PR

• Adds a github action and docs for use in downstream SDK repos to make sure that the SDKs have adequate test coverage and appropriately flag where and how each component of the tests are validating the spec.

Related Issues

#258
This is stacked on #388 and #388 should be merged first.

Follow-up Tasks

• Implement this in all the SDK repos that are >= 1.0 as a required test, and for all non 1.0 make this a non-required action.
• Update existing 1.0+ descriptions where they've fallen out of date
• Identify/create tickets for any gaps in test coverage for the spec in 1.0+ repos

[gemini-code-assist]

Code Review

This pull request introduces a new GitHub Action for OpenFeature spec compliance checking, along with updated documentation, examples, and minor bug fixes in the Python parser. The code review highlights several critical improvements: using a stable Python 3.13 version instead of the unreleased 3.14 in the Dockerfile and Ruff configuration, conditionally replacing the inline comment prefix in spec_finder.py to avoid redundant string operations, and replacing the openssl dependency with a native bash variable for generating random delimiters in the GitHub Action to ensure compatibility across minimal runner environments.

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