Added C# implementation of System.Math.ScaleB and System.MathF.ScaleB… (#42476)

Added C# implementation of System.Math.ScaleB and System.MathF.ScaleB… (#42476)

* Added C# implementation of System.Math.ScaleB and System.MathF.ScaleB, removed old bindings, added test cases.

* Moved tests into System.Runtime.Extensions tests.

* Removed unmanaged scalbn and scalbnf from pal and mono

* Update src/libraries/System.Private.CoreLib/src/System/Math.cs

Co-authored-by: Adeel Mujahid <adeelbm@outlook.com>
* Styling changes.

* Conditionally include ScaleB for Mono.

* Update src/mono/mono/metadata/sysmath.c

Tabs, not spaces.

Co-authored-by: Adeel Mujahid <adeelbm@outlook.com>
* Removing more scalb from PAL

* Completely removed ScaleB from Mono

* Cleaning up more scalbn

* Added comments for ScaleB, updated licenses for musl and Sun

* Fixed whitespace.

* Removing old references, fixing double ScaleB definition that merge didn't resolve

Co-authored-by: Adeel Mujahid <adeelbm@outlook.com>