FlxInput: Add Hold state/bool

[Lasercar]

Title. Why? Because Pressed and Just_Pressed return true at the same time it makes it impossible to only run or not run something if one of the keys of an action is already held down.

Modifying the behaviour of FlxInput to to make pressed only start returning after a frame might break some existing code, so add a new state called Hold that only returns true after the key's held for more than one frame?

I need this change in order to properly finish/fix this PR of mine:

FunkinCrew/Funkin#4145

[Geokureli]

makes it impossible to only run or not run something if one of the keys of an action is already held down

Just use this?

if (FlxG.keys.pressed.SPACE && false == FlxG.keys.justPressed.SPACE)

[Lasercar]

makes it impossible to only run or not run something if one of the keys of an action is already held down

Just use this?

if (FlxG.keys.pressed.SPACE && false == FlxG.keys.justPressed.SPACE)

Hmm, I'll try making a check for this with the controls - if one of the keys returns this, then return false.

[Geokureli]

if one of the keys returns this, then return false

the code I gave is a check to see if the space key was held, I imagine a check would use this to return true, not false.
example:

function isKeyHeld(key:FlxKey)
{
    return FlxG.keys.checkStatus(key, PRESSED) && false == FlxG.keys.checkStatus(key, JUST_PRESSED)
}

[Lasercar]

the code I gave is a check to see if the space key was held, I imagine a check would use this to return true, not false. example:

function isKeyHeld(key:FlxKey)
{
    return FlxG.keys.checkStatus(key, PRESSED) && false == FlxG.keys.checkStatus(key, JUST_PRESSED)
}

Yeah, that's my bad.