GDScript: Fix Inspector "Add Input" button, improve tweening, add pri… #112

Job	Run time
Building Engine / Windows Editor	9m 17s
Building Engine / MacOS Editor	34m 46s
Building Engine / Linux Editor	14m 22s
Building Engine / Windows Template	9m 18s
Building Engine / MacOS Template	21m 48s
Building Engine / Linux Template	2m 22s
🏁 Build Windows Dev PR / Build	6m 39s
🐧 Build Linux Dev PR / Build	3m 35s
🍎 Build MacOS Dev PR / Build	5m 42s
	1h 47m 49s

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