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.

首先查看现有可执行文件的版本输出和 pull request #8，然后检查当前如何处理命令行选项。完成的标准是，用户可以通过 full-version 选项区分此实现，并且具有所提议的帮助行为，同时保留现有的数字版本输出。