feat: add convert_boxed and insert_boxed for InstructionTable

[Rjected]

This adds a test which serves as an example for adding custom instructions which require some context. This also adds convert_boxed and insert_boxed which should make it easier to do this using the revm builder.

[mattsse]

should we convert to boxed instead?

[rakita]

I would panic here. Silently converting can have a side-effect on performance

[mattsse]

but there's no other way to use custom instructions, the only way is to box all of them, so I think it'd be reasonable to convert here

[rakita]

It should be intentionally called with to_boxed not silently converted.

[mattsse]

this would make evm setup fallible and force unwrap with a preceding call to to_boxed, i think this makes it a lot less convenient to use, and since additional instructions are only supported by boxing all of them, converting them here seems reasonable to me

[rakita]

That is the point to fail and make it explicit to call, this would look something like.

table.convert_to_box();
table.insert_boxed(instr);

It is redundant but explicit on what is going on.

Not the point I would die on, so lets convert it to boxed inside insert_boxed.

[Rjected]

Changed to convert into the boxed variant inside insert_boxed. updated docs and the test which no longer needs a map