* Centralise version scripts and fix Docker version
* Refactor generation of a git-hash-based version into get-version-from-git
* Refactor normalization of versions (stripping leading v) into normalize-version.sh
* Call get-version-from-git from ci_package.sh, call normalize-version from package.sh
* Refactor docker-write-version.sh into docker-package.sh, which both writes the
version file and invokes yarn build passing VERSION
* Normalize the version received from the server
Fixes https://github.com/vector-im/riot-web/issues/11864
This uses an environment variable because the build script assumes you want a production build, but we don't for this particular script. To avoid having a mess of NPM scripts to worry about, we'll just pass a flag down.