Add support for generic fields

[mratsim]

This fails with "Unexpected bracket expression array[" as genny tries to call getTypeInst on a A[B].

genny/src/genny/internal.nim

Lines 92 to 97 in 33f0e5a

	internal.add &"proc $lib_{objNameSnaked}*("
	let objType = sym.getType()
	for fieldSym in objType[2]:
	let
	fieldName = fieldSym.repr
	fieldType = fieldSym.getTypeInst()

import genny

type
  Foo = object
    val: array[3, uint64]

proc sum(r: var Foo, a, b: Foo) =
  for i in 0 ..< r.val.len:
    r.val[i] = a.val[i] + b.val[i]

exportObject Foo:
  procs:
    sum(Foo, Foo, Foo)

writeFiles("bindings/generated", "test")
include generated/internal