* upstream/master: (241 commits)
  Allow pattern matching `null` against pointer types when the pointer types contain nested type parameters (dotnet#49915)
  Remove document extension method and convert usages to use the text buffer extension method.
  VB: Strengthen implementation of `PropertySymbol.IsWritable` against NullReferenceException (dotnet#49962)
  Add switch to skip nullable analysis (dotnet#49876)
  Update dependencies from https://github.com/dotnet/roslyn build 20201211.16 (dotnet#49958)
  Treat record positional parameters as properties (dotnet#48329)
  [master] Update dependencies from dotnet/roslyn (dotnet#49395)
  VB: Ensure array access indexes undergo conversion to integer even when there is a mismatch with array rank. (dotnet#49907)
  Disable OOP when running as cloud environment client VS instance
  Rename workspace context method (and unify impls) to better represent the condition being checked
  Report non-Const locals used in an expression that must have a constant value. (dotnet#49912)
  Add support for more ServiceAudience values (dotnet#49914)
  Handle ref-containing structs returned by value from function-pointers (dotnet#49883)
  Fix error on out param of extern local function (dotnet#49860)
  Fix constructor exit warnings for generic NotNull (dotnet#49841)
  Loc updates
  Prefer more specific path map key (dotnet#49670)
  Rename `_availablelocalFunctionOrdinal` to `_availableLocalFunctionOrdinal` (dotnet#49901)
  Fix namespace so that external access wrapper type can be accessed from UT.
  XamlProjectService fixes (dotnet#49711)
  ...