Simplify and fix some issues in /script command registration

[altrisi]

This PR refactors the /script command registration a bit, mostly to make it more clear when adding to brigadier and to fix some issues with it.

Summary of changes:

• /script in <app> will no longer silently use the default host when app isn't valid, but instead will fail
• Global /script actions such as stop or resume will no longer be repeated under each /script in <app>
• Suggestion initialization will no longer sort on insert but at the end, and will then use unmodifiable collections
• Hides /script download if app store is completely disabled
• Simplifies permissions: Now the whole /script is under the same rule
• No longer stores all individual subcommands in variables with meaningless names, but uses the typical fluent API of brigadier
• Removes unnecessary Stream->List conversions for some suggestions
• Makes all methods in multiline chains consistently have the dot at the start of the line instead of at the end of the previous one to prevent confusion with direct method calls

There may be more changes I've missed given most of this has been in a git stash for a while, though I think I got them all.