refactor: Move plugin.json-s to a common place

[d3xter666]

Adjust plugin repo to support more coding agents.
With this PR we target GitHub CoPilot: #38

plugins/*/plugin.json now has a skills property where the skills are listed.
According to awesome-copilot's GUIDELINES, they follow the Claude plugin schema where skills are listed. Also, many of the project inside awesome-copilot's repo have this property set.
GitHub CoPilot Plugin reference also lists this property: https://docs.github.com/en/copilot/reference/copilot-cli-reference/cli-plugin-reference

JIRA: CPOUI5FOUNDATION-1240

[d3xter666]

An example plugin with skills property within awesome-copilot project: https://github.com/github/awesome-copilot/blob/main/plugins/skill-image-gen/.github/plugin/plugin.json

[matz3]

Shouldn't we use https://docs.github.com/en/copilot/reference/copilot-cli-reference/cli-plugin-reference as the source of truth for Copilot plugins?
I'm certain that the awesome project is correct, but it is not the official project and I think we should rather reference the actual GitHub documentation.

[d3xter666]

Shouldn't we use https://docs.github.com/en/copilot/reference/copilot-cli-reference/cli-plugin-reference as the source of truth for Copilot plugins? I'm certain that the awesome project is correct, but it is not the official project and I think we should rather reference the actual GitHub documentation.

Do you mean the skills property by that?
If "yes", it's listed also in here: https://docs.github.com/en/copilot/reference/copilot-cli-reference/cli-plugin-reference

According to what we provide in plugins/*/plugin.json, we are now compatible with both- Claude & CoPilot

Am I missing something else?

Edit: I have udpated the description to link also to the GitHub CoPilot

[matz3]

No, I just noted that we should rather use the official tool documentation than a community-driven project for referencing the expected format of plugins.

[RandomByte]

Are you sure that we don't need a file /.github/plugin/plugin.json? I see this is all the projects I checked from https://github.com/github/awesome-copilot/blob/main/plugins/external.json