Allow generic to be left out in PropsWithChildren type

[jakst]

Many components take only children as a prop, and nothing else. Defaulting the generic helper type PropsWithChildren to {} allows the consumer to use it as simply props: PropsWithChildren instead of the awkward-looking props: PropsWithChildren<{}>.

[ryansolid]

Sound good.

[coveralls]

Pull Request Test Coverage Report for Build 995147843

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 90.196%

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Totals
Change from base Build 992416643:	0.0%
Covered Lines:	1055
Relevant Lines:	1119

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💛 - Coveralls