ThrowHelper proposal draft

[Mrnikbobjeff]

Description of Change

Draft for ThrowHelper, as our current Exception throwing policy may result in worse code generation and in code bloat.

• Related to issue [Enhancement] Use throwhelper in argument validation scenarios to be more inline friendly and reduce code size and improve generation #1415 and [Enhancement] Share feature throws different exceptions across platforms. #963 as well as SecureStorage.ios.cs throws improper Exceptions. #457

Behavioral Changes

More detailed Exceptions in SecureStorage.ios, but fully backward compatible as we only throw System.Exception.
PlatformNotSupportedExceptions were converted to NotImplementedExceptions as the type is not owned by us and has docs which make no sense as seen in linked issues

PR Checklist

• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Updated documentation (see walkthrough)
  @mattleibow

[Mrnikbobjeff]

So, it appears that the binary size did increase slightly. This is mostly due to the additional metadata for the new methods. The compiler is smart enough to detect throwhelper methods and not inline them as well as generate slightly better code for retuning of these fake throwhelper methods as you can see here. It is still true that the inlineability of these methods increases manyfold as method size goes down incredibly in some methods which do not require building an exception frame.