lldb: add more stage2 pretty printers

[jacobly0]

Use .unwrapped to view intern pool index payloads.

(lldb) v val
(root.Value) val = {
  .ip_index = @enumFromInt(156) repro2.Foo
}
(lldb) v val.ip_index.unwrapped
(root.InternPool.Index.Unwrapped) .unwrapped = {
  .tag = .type_struct
  .payload = {
    .name = @enumFromInt(6597) "repro2.Foo"
    .cau = @enumFromInt(313) {
      .zir_index = @enumFromInt(314)
      .namespace = @enumFromInt(8)
      .owner = (.kind = .type, .index = 156)
    }
    .zir_index = @enumFromInt(314)
    .namespace = @enumFromInt(8)
    .fields_len = 1
    .flags = {
      .any_captures = false
      .is_extern = false
      .known_non_opv = true
      .requires_comptime = .no
      .assumed_runtime_bits = false
      .assumed_pointer_aligned = false
      .any_comptime_fields = false
      .any_default_inits = false
      .any_aligned_fields = false
      .alignment = .@"8"
      .alignment_wip = false
      .field_types_wip = false
      .layout_wip = false
      .layout_resolved = true
      .field_inits_wip = false
      .inits_resolved = true
      .fully_resolved = false
      .is_reified = false
      ._ = 0
    }
    .size = 8
  }
  .trailing = {
    .captures_len = null
    .captures = null
    .type_hash = null
    .field_types = len=1 {
      [0] = @enumFromInt(158) *... repro2.Foo
    }
    .field_names_map = @enumFromInt(9)
    .field_names = len=1 {
      [0] = @enumFromInt(9217) "foo"
    }
    .field_inits = null
    .field_aligns = null
    .field_is_comptime_bits = null
    .field_index = {
      .field_index.? = len=1 {
        [0] = @enumFromInt(0)
      }
    }
    .field_offset = len=1 {
      [0] = 0
    }
  }
}

Note that without requiring .unwrapped, the above value would recurse infinitely trying to print a self-referential type.