Mod-tap: allow sending modifier immediately on key down

[lyallcooper]

As far as I can tell from the various configuration options around hold-tap, there is no way to replicate this desired behavior:

key: &mt LGUI ESC

Within tapping term (unless interrupted when using hold-preferred or balanced flavors):
key down: LGUI down event sent
key up: LGUI up event sent, then ESC down + up sent

When held longer than tapping term:
key down: LGUI down event sent
key up: LGUI up event sent

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Why this is useful:

This allows someone to e.g. GUI + click immediately after pressing the key, instead of having to wait for the tapping term to expire first.

[dxmh]

Somewhat related PR that may be useful to some:

• Marcoster/behavior key tap #1142

[akira-toriyama]

+1

[caksoylar]

#1811 would resolve this.

[akira-toriyama]

@caksoylar Thank you

[caksoylar]

Closing since #1811 handled it.