wasmparser: Increase MAX_WASM_COMPONENT_TYPE_DECLS to 1_000_000

[MangoPeachGrape]

I was hitting against a linker error when using wit-bindgen in Rust with more than 100k functions.

A simple wit file to reproduce this:

package x:xx;
world xxx {
	import a0: func();
	import a1: func();
	import a2: func();
	import a3: func();
        ...
        ...
	import a99999: func();
	import a100000: func();
}

The error:

  = note: some arguments are omitted. use `--verbose` to show all linker arguments
  = note: error: failed to parse core wasm for componentization

          Caused by:
              0: decoding custom section component-type:wit-bindgen:0.43.0:x:xx:xxx:encoded world
              1: component type declaration size is out of bounds (at offset 0x2c)

With this change I tested up to 200k functions with no problems.

Similar to #2087