add jbang catalog

[maxandersen]

This makes it possible to use jbang to easily run and install pkl jar based cli.

Once merged you will be able to run it like this:

jbang pkl@apple/pkl

you can also install it and then just use it as a script from wherever:

jbang app install pkl@apple/pkl
pkl --version

I include in this pr a renovate.json that enables automatic PR updates if you are able to install https://github.com/apps/forking-renovate on this repo.

if not, you will have to manually update the version - or we change the version used in jbang-catalog to RELEASE and it will fetch latest release always.

the build.yml is used to validate prs opened by renovate.

Thus if renovate is not an option I would remove those - for now just include it. Let me know and I can adjust PR.

[maxandersen]

pushed update with alias for java and kotlin code generator.

jbang app install pkl-codegen-java@apple/pkl

and

``jbang app install pkl-codegen-kotlin@apple/pkl`