Port to 1.8.9 (legacyfabric)

[moehreag]

somehow there are still people using this version, so they might as well get some of the queer.

Explanation of the new dependencies:

• fastutil needed to be added since Minecraft didn't already use back then.
• search-in-resources provides a resourceManager.findResources(...) like syntax for this version, which also didn't exist on 1.8.9.
• runtime dependency on log4j, otherwise logging breaks for this version of Minecraft in the dev env.

Other changes:

• replacement of var keywords, because Java 8 doesn't know them (yet)
• create a small method for Identifier parsing, since that didn't exist in MC's code.

If you consider merging this, maybe create a new branch to point it to in advance.