Disable redundant type annotation

[3Rafal]

This fixes #1036

The constrained pattern from example code

let my_fun (x : int) = x

is represented as below typedtree:

  structure_item (scratch.ml[1,0+0]..scratch.ml[1,0+24])
    Tstr_value Nonrec
    [
      <def>
        pattern (scratch.ml[1,0+4]..scratch.ml[1,0+10])
          Tpat_var \"my_fun/273\"
        expression (scratch.ml[1,0+11]..scratch.ml[1,0+24]) ghost
          Texp_function
          Nolabel
          [
            <case>
              pattern (scratch.ml[1,0+12]..scratch.ml[1,0+13])
                extra
                  Tpat_extra_constraint
                  core_type (scratch.ml[1,0+16]..scratch.ml[1,0+19])
                    Ttyp_constr \"int/1!\"
                    []
                Tpat_alias \"x/275\"
                pattern (scratch.ml[1,0+12]..scratch.ml[1,0+13])
                  Tpat_any
              expression (scratch.ml[1,0+23]..scratch.ml[1,0+24])
                Texp_ident \"x/275\"
          ]
    ]
]

Which means that we have to explicitly check for nested patterns of any and alias.

[rgrinberg]

LGTM. A test would be nice as well.

[3Rafal]

@rgrinberg, yes. I made this as a draft because there was no tests and changelog description. Just added them and now I think it's good. :)

[rgrinberg]

Could you try porting this test to OCaml in e2e-new?

The typescript suite is our legacy test suite. We haven't yet ported it to all to OCaml, but we'd like to stop adding new tests at least.

[3Rafal]

@rgrinberg , sure! I have ported them. After this PR gets merged I will port other type-annotate as well, so that they're all in one place. I already have the filtering functionality, so it should be a simple refactor.