Please make it possible to distinguish between implementations

Currently there is the main repository at https://github.com/LuaLS/lua-language-server and this rust rewrite. Both contain very similar language servers using identically named executables. While the long term plan might be for this one to either replace or get integrated into the other one, and thus there might be no desire for a name change, their colliding nature is problematic right now as they require being configured differently to be fully usable.

How about adding a way to query the executable of which implementation this is. One could imagine --version to output the information, but as it currently only outputs the numeric version that might be considered a breaking change. An alternative would be to add an additional --full-version flag including the name of the implementation, as done in pull request #8 accompanying this issue. That change also makes it possible to get a fuller version string using git rather than merely the approximate version parsed from the changelog. Additionally it adds a very rudimentary --help option which I'm not sure is correct. Please feel free to rewrite the commit for partial inclusion if desired.

In the quite likely event that the pull request is not possible to merge as is, minor suggested changes directly in it are welcome as well as keeping a supposedly more high level discussion in this issue.

Review the existing executable version output and pull request #8 first, then check how command-line options are currently handled. Done means users can distinguish this implementation with a full-version option and have the proposed help behavior, while preserving the existing numeric version output.