Adjust 'BOMB' category usage and add torpedo/normal bomber selection hotkeys

[lL1l1]

Description of the proposed changes

Closes #5298. Reduces the need to manually filter after using the select all bombers hotkey. Could be done with game.prefs editing instead, but it seems useful enough to be a default available to all players.
BOMB category and Suicide Weapon ability text removed from Loyalist because it no longer has the self-destructing charge ability.
BOMB category added to Mercy because it has to die to attack, just like the fire beetle.

Testing done on the proposed changes

Spawned all torpedo bombers and all bombers + mercy. Pressing the select all bombers (non-torpedo) hotkey selects all normal bombers. Pressing the select all bombers (torpedo) hotkey selects all torpedo bombers. Mercy does not get selected.

Checklist

• Changes are annotated, including comments where useful
• Changes are documented in the changelog for the next game version

[relent0r]

Nice change on the Mercy. Until now if I want to capture all MOBILE AIR BOMBER I've always had to exclude the Mercys unit id since from a category perspective you can't tell the difference.

[Garanas]

@lL1l1 can you add the category and descriptions for the new hotkeys to the changelog? That way players do not have to go searching for them

[lL1l1]

One thing I noticed is that this would make it more difficult to identify Loyalist's death weapon usage since there's no category for it anymore. BOMB is for suicide weapons, and VOLATILE is for units who's death effects should be stopped by reclaiming (this doesn't work though). VOLATILE category is also a separate definition from the ability text displayed in the UI, which just means a unit has a death weapon.