[firmware] Add better versioning scheme

[kbhomes]

Goals for a better versioning scheme:

• Support a more human-readable identifier (like SemVer)
  • Currently using a uint16_t as a flat number for the version number
  • Consider changing to something like uint64_t, with a byte pattern such as:
    • Major: 1 byte
    • Minor: 2 bytes
    • Patch: 4 bytes
    • Metadata: 1 byte (for example, dev for local builds, latest for automatic builds)
• Automatically bump patch version with every commit (?)
• Automatically create versioned and latest GitHub releases on commits
  • Use ps2link's GitHub Actions workflow as an example
  • Briefly:
    • For all commits, create a latest release that is tagged as prerelease
    • For commits which are tagged

Not sure what the best strategy is for making sure the versions in the application and in Git stay in sync. Maybe keep major/minor in code, and patch and metadata passed in from the environment. Patch number might be "number of commits since last tag", and tags will always be "<major>.<minor>.0". This could be problematic if the commit history isn't linear -- need to think about that.