Add support for ranged item amounts in Give and GiveAll commands

[AerWyn81]

This pull request adds support for specifying a random amount range when using the give and giveall server item commands. Users can now enter an amount as a single number or as a range (e.g., 1-10), and the command will randomly select an amount within that range. Additionally, tab completion has been updated to suggest common ranges.

Command functionality improvements:

• Added support for amount ranges (e.g., 1-10) in the give and giveall commands. The code parses the range, validates it, and randomly selects an amount within the specified range.

Tab completion enhancements:

• Updated tab completion for the amount argument in both Give.java and GiveAll.java to suggest common ranges like 1-10 and 1-64, in addition to single values.

Tested in production.

[TheOne-Player]

Thank you for your PR @AerWyn81!
This looks useful, thanks for adding range support. One thing to clarify: when an amount range (e.g. 1-10) is passed to giveall, does the command sample a single random value and give that same amount to every target, or does it sample independently for each target? That distinction is potentially surprising to users.

Could you:

• State the intended behavior in the command help/usage text (and in the PR description).
• If you want to support both modes, consider adding an explicit option/flag (for example --per-target or --same-for-all) or a config setting so users can choose the behavior.
• Add a small test or example in the help showing the difference.

This will avoid confusion when people run giveall expecting either identical or per-player randomized amounts.

Why: users will reasonably expect either behavior and the current PR text doesn't say which one is implemented. Making it explicit (or adding a flag) avoids accidental surprises.