[ruby/prism] Change numbered parameters

Previously numbered parameters were a field on blocks and lambdas
that indicated the maximum number of numbered parameters in either
the block or lambda, respectively. However they also had a
parameters field that would always be nil in these cases.

This changes it so that we introduce a NumberedParametersNode that
goes in place of parameters, which has a single uint8_t maximum
field on it. That field contains the maximum numbered parameter in
either the block or lambda.

As a part of the PR, I'm introducing a new UInt8Field type that
can be used on nodes, which is just to make it a little more
explicit what the maximum values can be (the maximum is actually 9,
since it only goes up to _9). Plus we can do a couple of nice
things in serialization like just read a single byte.

https://github.com/ruby/prism/commit/2d87303903

1 files changed, 1 insertions, 2 deletions

diff --git a/test/prism/snapshots/seattlerb/block_decomp_arg_splat_arg.txt b/test/prism/snapshots/seattlerb/block_decomp_arg_splat_arg.txt
index 4c1a9976bf..caeda850b0 100644
--- a/test/prism/snapshots/seattlerb/block_decomp_arg_splat_arg.txt
+++ b/test/prism/snapshots/seattlerb/block_decomp_arg_splat_arg.txt
@@ -45,6 +45,5 @@
             │   │   └── closing_loc: (1,15)-(1,16) = "|"
             │   ├── body: ∅
             │   ├── opening_loc: (1,2)-(1,3) = "{"
-            │   ├── closing_loc: (1,17)-(1,18) = "}"
-            │   └── numbered_parameters: 0
+            │   └── closing_loc: (1,17)-(1,18) = "}"
             └── flags: ∅