Extension shuffling (#23291)wip/sand-witch/modern-STV-extension-shuffling

Where introduced 4 new extensions:
  - PatternSignatures
  - ExtendedForAllScope
  - MethodTypeVariables
  - ImplicitForAll

Tasks of ScopedTypeVariables extension were distributed between
PatternSignatures, ExtendedForAllScope and MethodTypeVariables according
to the proposal. Now ScopedTypeVaribles only implies these three exntesions.

Extension ImplicitForAll saves current behavior. NoImplicitForAll
disables implicit bounding of type variables in many contexts.

Was introduced one new warning option: -Wpattern-signature-binds
It warns when pattern signature binds into scope new type variable. For
example:

  f (a :: t) = ...

1 files changed, 3 insertions, 3 deletions

diff --git a/compiler/GHC/Tc/Deriv/Generate.hs b/compiler/GHC/Tc/Deriv/Generate.hs
index 9a76c82b8f..b8678e4344 100644
--- a/compiler/GHC/Tc/Deriv/Generate.hs
+++ b/compiler/GHC/Tc/Deriv/Generate.hs
@@ -1875,9 +1875,9 @@ of the method. For example, recall:
                   join
 
 In the example above, it is imperative that the `a` in the instance signature
-for `join` scope over the body of `join` by way of ScopedTypeVariables.
-This might sound obvious, but note that in gen_Newtype_binds, which is
-responsible for generating the code above, the type in `join`'s instance
+for `join` scope over the body of `join` by way of ExtendedForallScope (implied
+by ScopedTypeVariables). This might sound obvious, but note that in gen_Newtype_binds,
+which is responsible for generating the code above, the type in `join`'s instance
 signature is given as a Core type, whereas gen_Newtype_binds will eventually
 produce HsBinds (i.e., source Haskell) that is renamed and typechecked. We
 must ensure that `a` is in scope over the body of `join` during renaming