Figure out how to deal with versioning after migrating off TC

[BeeWarloc]

Now that we're migrating off TC we should figure out a new way to handle versioning of builds. Ideally the same method should also be usable for uno and fuselibs repos.

Things to consider:

• Should we take our version from a tag, or use from VERSION.txt as we do today?
• Should our snapshots and pre-releases be based on the previous or next version number?
• Should a local build of release commit X.Y.Z have version number X.Y.Z or X.Y.Z-somesuffix?

If we get our versions from tags I know of at least two alternatives we could use:

• git describe
• GitVersion

[BeeWarloc]

Currently the way we handle versions in scripts when built locally is a bit of mess.

In pack.sh version is set to the content of VERSION.txt with -local suffix added.

In the macOS installer build.sh the version string is set to a combination of timestamp and commit hash.

Also we don't update the AssemblyInfo versions. I got a WIP branch for that here, but not yet sure about the approach.