fix: CRW-4859 fix extension builds

[mkuznyetsov]

This PR contains multiple fixes and updates:

• update README.md with relevant information about the project
• added archives to .gitignore.
• most of extensions were not buildable, because current ubi8image nodejs18:1-60 comes with a version that doesn't work with the latest version of npm. So it will be updated to the newer version nodejs-18:1-71.1698060565
• with that, some more extensions started to fail their build on newer image, because of too many open files error in npm. Because new image now features limits set in them, a ulimit override flag was added to podman build
• build.sh script will not update manifests in plugin-manifest.json, unless new flag --update-manifest is set.It should make for a better developers workflow. who while trying to build these plugins locally would rather not want to create & commit changes to manifest, as only the Jenkins job should do it, when it builds them after merges to main branch.
• buiild.sh script --clean flag is updated, instead of doing system prune, it would just remove the final builder image, and base layer images won't have to be redownloaded, when developers/Jenkins are building more than 1 plugin.
• update project-config.json with newer revisions, that were not reachable anymore

this PR has to be merged in conjunction with another DS Jenkins PR https://gitlab.cee.redhat.com/codeready-workspaces/crw-jenkins/-/merge_requests/1746

[amisevsk]

LGTM in general, though I have a few comments about mixing upstream and downstream work here. A few suggestions on that front (though if this PR is needed soon we can merge as-is and discuss later). Nevermind, I had it in my head that this was a Che repository :)