Tree-sitter grammar: support the remaining signed and unsigned Int types

[OceanOak]

Changelog:

Tree-sitter-darklang
- Expand the grammar to support the remaining signed and unsigned Int types (Int8, Int16, Int32, Int64, Int128), and update the parser accordingly

#5321

[OceanOak]

Question:

We currently don't support negative integers (because of digits: $ => /\d+/,)

• I've added positive_digits and negative_digits (because uints will only have positive numbers)
• Made digits choice($.positive_digits, $.negative_digits)

The solution provided in this PR works. but I don't know if it is better to update the rule to something like the following instead. Feedback is appriciated

int64_literal: $ =>
  seq(
    field("sign", optional("-")
    field("digits", $.digits),
    field("suffix", alias("L", $.symbol)),
  ),

[StachuDotNet]

Could you please add a single comment somewhere around the Ints, indicating that we're only using .NET suffixes for Ints temporarily until we can get rid of the old parser?