Correctly parse partial objects with optional value

[christophpurrer]

Summary: The flow parser always returns if a property IS optional (true|false) OR not

The TypeScript one only emits optional if the prop is optional.

The current partialProperty UTs are not correct.

Changelog: [General][Fixed] - Correctly parse partial objects with optional value

Differential Revision: D56689387

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	19,461,330	-1
android	hermes	armeabi-v7a	n/a	--
android	hermes	x86	n/a	--
android	hermes	x86_64	n/a	--
android	jsc	arm64-v8a	22,834,250	-2
android	jsc	armeabi-v7a	n/a	--
android	jsc	x86	n/a	--
android	jsc	x86_64	n/a	--

Base commit: bb2c13af5372856cf3f4222ad6543d4698919dbc Branch: main