Part of #638 

### Outline

The new definition is used to construct the grammar definition model
from the DSL v1, which is then used by the codegen to create the parser
and rule/token kinds, like before.

The rough translation done here is to translate every
struct/enum/repeated/separated/precedence expression as a
rule/non-terminal kind (with the exception of choice nodes, which are
inlined, as per
#650 (comment));
the rest (i.e. trivia, fragment, token, keywords) are translated as
"old" tokens/terminals.

### More context

In general, this requires more polish and decision which rules are we
comfortable with leaving and fixing leftover issues such as explicit
`PrecedenceExpression#rule_name` added to fit the old DSL v1
model/codegen better.

I specifically didn't want to touch the v1 codegen/model yet, because it
helped being able to incrementally migrate to a new definition and I
wanted to limit changes done in a single PR, so that it's easier to
review. We can modify the codegen/model to fit the v2 model better once
we fully migrate and remove the old DSL v1.

The translation/construction is done at build "run-time" rather than
inside the newly introduced definition "compiler" proc macro. There's
not much explicit reason for that, other than the fact that it was
quicker for me to work on (quicker dev cycle) and the logic is just
plain Rust code. This can be moved inside the proc macro later on, if we
decide that it's better that way.

### Differences

Because the DSL v2 takes a more named and structured approach (as it's
designed to be a model for the strongly typed CST/AST), translating it
1-1 to our current parser structure is impossible or even desired.

There are some rules that were introduced and it doesn't make much sense
for some to replicate the old behaviour.

1. At the moment, it's impossible to specify an optional *separated*
item, so the following ones are introduced as wrappers:
   - `TupleValue` (used in `TupleValuesList`)
   - `TupleMemberDeconstruction` (used in `TupleMembersList`)
2. Some sequences in the structs are optional, but these are now
introduced and named, rather than inlined as before:
    - `IndexAccessEnd`
    - `ImportAlias`
    - `UsingAlias`
    - `VariableDeclarationValue`
3. ~Previously inlined sequence parsers now have to be named~ (fixed
with #657)
- `NumericExpression` is now split into two, now named, choices:
`HexNumberExpression` and `DecimalNumberExpression`
    
Moreover, the following was done to bring back the old CST shape as much
as possible:
- Some of the new rules where renamed back to the old ones, e.g. some
repeated nodes have `List` suffix again
- The (Yul)Statement are outlined (as in v0/v1) and re-introduced as a
struct wrapper
- `ArgumentsDeclaration` is outlined (as in v0/v1) as well
- `FunctionCallOptions` is outlined again as a `(NamedArgs NamedArgs*)`
rather than `NamedArgs | NamedArgs+` to better match the old CST in the
singular case (but differs from the old CST in the multiple case)
- #653 

This was done to unify the definitions where possible and to help with
reviewing the CST changes by minimizing the shape differences. Once we
move off v0 (#637) and v1 (#638), we will be free to change the final
shape, since the old definitions will stop tying us down quite a bit.
    
### Outstanding issues
- [x] Separate outstanding FIXMEs that need to be done after the
migration into a task list
   * LeadingTrivia in v2 is using the v1 definition for now
* SourceUnit is hacked to always be followed by Leading Trivia (copies
v1; trivia model in v2 is a bit different)
* Clean up `PrecedenceExpression#rule_name` and adapt the codegen model
to fit the v2 definition better
   * Stop leaking identifiers by adapting either v1 or v2 models
* Keyword trie inclusion should be reworked to not require synthetic
rules over all keywords (v1 model) and to properly allow keywords to
overlap identifiers (#568)
- [x] Fix the Prettier error caused by newly possible nested, empty
rules:
```
[error] crates/solidity/testing/snapshots/cst_output/TupleExpression/empty/generated/0.4.11-success.yml: SyntaxError: All collection items must start at the same column (11:9)
[error]    9 |   - TupleExpression (Rule): # 0..3 "( )"
[error]   10 |       - OpenParen (Token): "(" # 0..1
[error] > 11 |       - TupleValuesList (Rule): [] # 1..1
[error]      |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error] > 12 |           - TupleValue (Rule): [] # 1..1
[error]      | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error] > 13 |       - CloseParen (Token): ")" # 2..3
[error]      | ^
[error]   14 |
```