Going forward our release branches will all be under release/*. This
adds a glob for release/* so future release branches will just work. It
also removes all the old branches to which this change will not flow.

The shorter job name means the matrix name is visible in the list.

* Run CI builds for 16.0 preview2 vs-deps PRs

* Trigger branch builds on commit for preview branches

Azure Pipelines now supports us putting the branches which trigger PR
and CI validation into the YAML files. This change puts the current
contents of our build definition into the YAML files and updates our
creating feature branches document.

Note: i have not yet changed our build definition to read this
information. Want to commit this, give it a day to flow to the branches
then I will flip our definition over.

* Remove RuntimeIdentifier specification

* Arcade directory layout

* Add unmanaged generic struct tests

* Don't bail out of managed type checks when type arguments are present

* Simplify test

* Delegate HasPointerType to underlying field in WrappedFieldSymbol

* Add test for recursive expansion of struct with T : unmanaged

* Delay constraint checking on field types until after type members are added

* Update comment

* Add expected diagnostic to UnmanagedRecursiveTypeArgument test

* Add unmanaged recursive type argument tests with constraint violations

* Don't search fields whose type is circular struct when determining if a type is managed

* Update some tests

* Use TypeSyntax.Location for Type.CheckAllConstraints

* Add prototype comment

* Update GenericConstraintsTests

* Update IsManagedType asserts in UnsafeTests

* Fix ManagedAddressOfTests.DisallowSizeof

* Use SourceMemberFieldSymbol.SyntaxNode.Location for consistency in diagnostics

* Add some tests and diagnostics

* Fix more tests

* Fix BaseClassTests

* Add test for partially constructed generic struct which violates unmanaged constraint

* Consider nullability when running AfterTypeMembersChecks

* Update NullableReferenceTypesTests.Constraint_Oblivious due to differences from delayed constraint checks on field types

* Check if NRT enabled in compilation to use correct nullability in constraint checks

* Make UnmanagedConstraint_StructMismatchInImplements behave consistently

* Disable ResourceTests.AddResourceToModule in Mono

* Remove prototype comment

* Remove invalid comments from UnmanagedConstraints_NestedInGenericType

* Use ErrorLocation instead of SyntaxNode.Location

* Rename our pipeline YAML files

Originally created when everything was VSTS. This gets us back inline
with the new branding.

* Fix tests now that we use ErrorLocation for field constraint checks

Originally created when everything was VSTS. This gets us back inline
with the new branding.

* Use Arcade testing targets

* Skip CodeStyle tests on Mono

* Include net472 in test target frameworks for Mono

* Remove incorrect file existence check.

* Update ADO integration test yaml

Originally created when everything was VSTS. This gets us back inline
with the new branding.

Originally created when everything was VSTS. This gets us back inline
with the new branding.