PR comment for OpenAPI Diff output

[uniqueg]

• Do not fail when OpenAPI Diff action errors
• Instead, create PR comment with error log
• Currently does not work because of permission issues (403 on trying to create comment); may need to set PAT in github-script action, but don't have permissions to do that for this repo
• Otherwise works fine

Produces output like this:

diff.md

[Copilot]

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

[vsmalladi]

@uniqueg still issue with permissions. But got a workaround to upload the artifact with error log.
diff-artifacts (2).zip

[vsmalladi]

@uniqueg I think i fixed this.

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again, by re-requesting a review.

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.

[vsmalladi]

All changes look good. Merging in now.