Intrinsify Encoding.TryGetBytes for UTF16 -> UTF8 literals

[EgorBo]

Tracking issue for @stephentoub's request in #84609

The idea that we should provide zero-cost conversion from UTF16 to UTF8 for string literals/RVA data in order to have efficient UTF8 string interpolation.

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Issue Details

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Tracking issue for @stephentoub's request in #84609

The idea that we should provide zero-cost conversion from UTF16 to UTF8 for string literals/RVA data in order to have efficient UTF8 string interpolation.

Author:	EgorBo
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-