* Prevent invalid byref types when declaring functions/methods

* Fixed abstract slot not erroring on invalid types with byrefs

* Added tests

* Added more tests

* Added more tests, updated baselines, renamed NoneInner to NoInnerByRef and it only checks for byref

* More tests. Updated baseline. Trying to error on functions/methods that are invalid.

* Updating vs baseline

* Fixed baseline

* Updated baselines. Simplified checking a type.

* Prevent crash

* Fixing some issues

* Updated baselines. Make checks a bit simpler

* Small cleanup

* Fixed build

* Quick update

* Trying to fix build

* Updated neg107 baselines

* Added more descriptive error messages for checking declared functions/methods for byrefs

* Updated buildfromsource

* Fixed merge

* Fixed build

* Stop UnifyTypes recovery in TcDelayed

* Added test

* Added baseline

* Added neg108 test

* Showing a better error message when trying to take an address of an operation

* Updated tests/baseline\

* Updated baselines

* Code cleanup

*  Fixed crash. Disallowing unapplied byref exstension methods. Updated some erorr messages.

* Updated some tests

* Quick update on method name

* Updated buildfromsource

* Updated error message

* Renamed method

Merge dev15.8 to dev15.9

Rev'ed Roslyn package version to fix glyph tags

* Fixed overloading for inref/outref/byref from passing

* Normalizing test names

* Disallow optional type extensions on byref types

* Normalizing test names

Fixed extension members that extend a type using a byref to be called with an immutable value (#5447)

* Fixed extension members that extend a type using a byref to be called with an immutable value

* Added more tests, but no updated baseline yet

* Updated baselines

* Minor cleanup

* Fixed tests. Fixed output of tests

* Updated buildfromsource

* Minor cleanup

Merge dev15.8 to dev15.9

rename old YAML files

rename old YAML file

[dev15.8] rename YAML build definition

[dev15.9] rename YAML build definitions

Merge dev15.8 to dev15.9

Cherry-pick VSTS CI to dev15.9

Cherrypick 3 --- better fix for #5369 (#5398) 

Merge dev15.8 to dev15.9

Signing