feat: improve Paper/Spigot Gradle plugin templates

[Strokkur424]

Requires minecraft-dev/MinecraftDev#2574 to be merged alongside.

This PR improves the default Paper/Spigot plugin templates by changing the following things:

• Only generate Gradle scripts with the Kotlin DSL
• Give users a choice to add the run-paper and shadowjar plugins if they so desire
• Move the project version and group declaration to gradle.properties
• Add some performance enhancing properties to gradle.properties
• Remove unnecessary java version configure logic
• Add a .gitattributes file
• Bump the Gradle plugin versions used
• Always use the latest available Gradle version, ensured by running gradle wrapper --gradle-version=latest
• Optional userdev plugin inclusion toggle
• Optional toggle for Gradle version catalog (libs.versions.toml)
• Paper PluginLoader file creation toggle
• Paper PluginBootstrap file creation toggle
• Gremlin Gradle plugin for automatic runtime download

[Amejonah1200]

Why not manage this version in the version catalog with

kotlin("jvm") version libs.versions.kotlin.get()

?

[Strokkur424]

I've decided against it because it was also decided (I did ask the MCDev people about this) that we do not want to have the Java version in that version catalog, as that is a rather uncommon thing to do. In the same spirit I also think the version catalog should not contain the Kotlin version. This is a very minor thing to worry about though IMO.

[Amejonah1200]

Both Kotlin and Java are dependencies to the project (stdlib in particular) tho.
This would also allow to only make changes for newer versions (like using renovate) in a single file instead of build scripts.

Is it feasible to make it an "advanced" toggle, then? (is there even an "advanced" section even?)

[Strokkur424]

I guess