Preview PRs in playground

[hatemhosny]

This PR adds github actions to preview PR changes in playground. See Preview in LiveCodes.

It uses pkg.pr.new to load Ripple compiler, runtime and formatter so that they can be tried in the playground before merge.

Example: hatemhosny/racing-bars#211 (comment)

Please note:

• The GH actions need to be merged to the main branch to work (details).
• This needs the pkg.pr.new packages to be available.

[leonidaz]

thank you!

let's merge and see

[hatemhosny]

@leonidaz
So, it did post the comment with a link to playground: #122 (comment)

However, the files were not loaded in the playground because pkg.pr.new workflow did not publish the packages, because of lack of collaborator approval:
PR is approved by collaborator: false

[leonidaz]

@hatemhosny it's because from non-contributors it requires a manual approval to run. Could your job depend on pkg.pr run so then they're synced.