Sound Fix for DropDownButton Widget
Normalizing CashTicks AUD for TD
Remove duplicated IronCurtainable rules.
Add a UnitUpgradeManager trait.

This introduces support for timed upgrades, starting with crate buffs.
Fix cloak upgrade expiration.
Reimplement iron curtain as a generic stat upgrade.
Add the invulnerability crate to RA.
Add a GrantUpgradeWarhead and initial TS EMP implementation.
Replace RemoveOnConditions with KillsSelf.

Upgrades offer more flexibility than prerequisites.
Detonate demo trucks when they are iron-curtained.
Rename UnitUpgradeCrateAction to GrantUpgradeCrateAction.
Expose upgrades to map scripts.
Remove the now-redundant ScriptInvulnerable trait.
Merge pull request #6621 from steelphase-forks/bleed-soundfix

Sound Fix for DropDownButton Widget
Scroll Panel Sound

Adds sound to Up, Down, and Thumb Button
Merge pull request #6627 from s1ww/cnc_cash_ticks

Normalizing CashTicks AUD for TD
Harvester now autoharvest when produced
Merge pull request #6634 from abcdefg30/autoharvest

Let harvesters autoharvest when produced
Merge pull request #6623 from steelphase-forks/bleed-ScrollPanelSound

Scroll Panel Sound
Extended IMove for Enter logic