schema: add compatibleNcs field to schema and filter based on ncs

[FilipZajdel]

VSC-2486

[datenreisender]

In the README.md the new property compatibleNcs should also be mentioned in this list: https://github.com/nrfconnect/ncs-app-index/blob/main/README.md?plain=1#L44-L51

[datenreisender]

Was this file added by mistake? Should it be in .gitignore?

[bencefr]

I was hoping that compatibleNcs could be a single semver condition instead an array of distinct versions. Semver inherently deals with the leading v that is quite madly prepended to tags, and a single string like 1.x || >=2.5.0 || 5.0.0 - 7.2.3 can qualify a given version quite well. I don't know if including the branches (i.e. main) is necessary though, so I'm a bit puzzled to fight for this.

[datenreisender]

I also thought that adding support for specifying semver ranges would be nice, because with it there would be less need to update the <app>.json files. But maybe this could also be a future addition.

And, yes, this gets tricky because tags and branches could really be named anything.

An idea:

• We could stick with an array, || the elements together, and do a loose semver range match against the tags/branch.
• Additionally we can make a equality check with every array element against the tags and if they match then we also include those.

With this one could e.g. write ['main', '1.x', '>=2.5.0 <3.0.0', '~4.2', '5.0.0 - 7.2.3'].