Update function should support alternative servers better

[sandain]

The current update function really only works well for vanilla release and snapshot servers. Other server types could be defined in mscs-version-type (e.g. bungeecord, forge, spigot, etc.) and used in the update function to allow for updating these alternative server types. This could greatly simplify our documentation and make server management much easier.

Issue noted by @Omig12. See https://github.com/MinecraftServerControl/MinecraftServerControl.github.io/issues/1

[sandain]

As noted in Issue #273 by @Xarius86, the PaperMC API can be found at: https://papermc.io/api/docs/swagger-ui/index.html?configUrl=/api/openapi/swagger-config

[sandain]

The current PaperMC API requires two https requests to download the latest server:

• https://papermc.io/api/v2/projects/paper/versions/$SERVER_VERSION/ gives a json file containing build numbers for the requested server version.
• https://papermc.io/api/v2/projects/paper/versions/$SERVER_VERSION/builds/$BUILD_NUMBER/downloads/paper-$SERVER_VERSION-$BUILD_NUMBER.jar gives the server jar file.