wast-parser remove extra generate names

[xtuc]

(module
  (global (export "v") i32 (i32.const 1))
)

and the corresponding AST is:

(module
  (global $global_0 i32 (i32.const 1))
  (export "v" (global $global_0)) 
)

The issues:

• the global declaration has no name and we are assuming they were
• doesn't match with the wasm-parser (which uses an offset)

I would propose to introduce indices in the state of the parser and change the identifiers with numberLitertals.

TODO: test to re-activate: https://github.com/xtuc/webassemblyjs/blob/0998ea34c48bb4f41ec9e0b2e903005af0632c94/packages/wasm-parser/test/fixtures/module-export/global/actual.wat-failure