[@microsoft.azure/openapi-validator-rulesets] Reduce package size by removing unnecessary files

[mikeharder]

Package @microsoft.azure/openapi-validator-rulesets is 8.5MB unpacked, because it contains a lot of unnecessary files, especially some large tests. Removing these files should reduce the download and disk sizes significantly, with no change to end-user functionality.

• Analyze the files in the package
• Determine which are likely required to maintain compabitility for package consumers, and which can likely be removed, like test code, test assets (input files), maybe source code if the "dist" version of the source is already included
• Create a PR to exclude these files from the package