`ruby2_keywords` is set only to be `0` in parse.y.
However `args->ruby2_keywords` is initialized with `0` by `MEMZERO`
in `rb_node_args_new` function and `body->param.flags.ruby2_keywords`
is initialized with `0` by `ZALLOC` in `rb_iseq_constant_body_alloc` function,
so `args->ruby2_keywords` does nothing for `body->param.flags.ruby2_keywords`.

Add locations to struct `RNode_SCLASS`.

memo:

```
@ ProgramNode (location: (1,0)-(1,18))
+-- locals: []
+-- statements:
    @ StatementsNode (location: (1,0)-(1,18))
    +-- body: (length: 1)
        +-- @ SingletonClassNode (location: (1,0)-(1,18))
            +-- locals: []
            +-- class_keyword_loc: (1,0)-(1,5) = "class"
            +-- operator_loc: (1,6)-(1,8) = "<<"
            +-- expression:
            |   @ SelfNode (location: (1,9)-(1,13))
            +-- body: nil
            +-- end_keyword_loc: (1,15)-(1,18) = "end"
```

This change makes `RubyVM::AST.of` and `.node_id_for_backtrace_location`
return a parent node of NODE_SCOPE (such as NODE_DEFN) instead of the
NODE_SCOPE node itself.
(In future, we may remove NODE_SCOPE, which is a bit hacky AST node.)

This is preparation for [Feature #21543].

Add locations to struct `RNode_IN`.

memo:

```bash
> ruby -e 'case 1; in 2 then 3; end' --parser=prism --dump=parsetree
@ ProgramNode (location: (1,0)-(1,24))
+-- locals: []
+-- statements:
    @ StatementsNode (location: (1,0)-(1,24))
    +-- body: (length: 1)
        +-- @ CaseMatchNode (location: (1,0)-(1,24))
            +-- predicate:
            |   @ IntegerNode (location: (1,5)-(1,6))
            |   +-- IntegerBaseFlags: decimal
            |   +-- value: 1
            +-- conditions: (length: 1)
            |   +-- @ InNode (location: (1,8)-(1,19))
            |       +-- pattern:
            |       |   @ IntegerNode (location: (1,11)-(1,12))
            |       |   +-- IntegerBaseFlags: decimal
            |       |   +-- value: 2
            |       +-- statements:
            |       |   @ StatementsNode (location: (1,18)-(1,19))
            |       |   +-- body: (length: 1)
            |       |       +-- @ IntegerNode (location: (1,18)-(1,19))
            |       |           +-- IntegerBaseFlags: decimal
            |       |           +-- value: 3
            |       +-- in_loc: (1,8)-(1,10) = "in"
            |       +-- then_loc: (1,13)-(1,17) = "then"
            +-- else_clause: nil
            +-- case_keyword_loc: (1,0)-(1,4) = "case"
            +-- end_keyword_loc: (1,21)-(1,24) = "end"
```

Add `keyword_module` amd `keyword_end` locations to struct `RNode_MODULE`.

memo:
```
>ruby --dump=parsetree -e 'module A end'
@ ProgramNode (location: (1,0)-(1,12))
+-- locals: []
+-- statements:
    @ StatementsNode (location: (1,0)-(1,12))
    +-- body: (length: 1)
        +-- @ ModuleNode (location: (1,0)-(1,12))
            +-- locals: []
            +-- module_keyword_loc: (1,0)-(1,6) = "module"
            +-- constant_path:
            |   @ ConstantReadNode (location: (1,7)-(1,8))
            |   +-- name: :A
            +-- body: nil
            +-- end_keyword_loc: (1,9)-(1,12) = "end"
            +-- name: :A
```

Add keyword_defined locations to struct RNode_DEFINED

Now that the shape_id gives us all the same information, it's no
longer needed.

The following Location information has been added This is the information required for parse.y to be a universal parser:

```
❯ ruby --parser=prism --dump=parsetree -e "class A < B; end"
@ ProgramNode (location: (1,0)-(1,16))
+-- locals: []
+-- statements:
    @ StatementsNode (location: (1,0)-(1,16))
    +-- body: (length: 1)
        +-- @ ClassNode (location: (1,0)-(1,16))
            +-- locals: []
            +-- class_keyword_loc: (1,0)-(1,5) = "class"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
            +-- constant_path:
            |   @ ConstantReadNode (location: (1,6)-(1,7))
            |   +-- name: :A
            +-- inheritance_operator_loc: (1,8)-(1,9) = "<"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
            +-- superclass:
            |   @ ConstantReadNode (location: (1,10)-(1,11))
            |   +-- name: :B
            +-- body: nil
            +-- end_keyword_loc: (1,13)-(1,16) = "end"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
            +-- name: :A
```