Compile 0 literals to the PUSH0 opcode

[Philogy]

Overview

Closes #279. Ensures that simple zero literals like 0x0 and 0x0000 compile to PUSH0 rather than the default PUSH1 0x00. Explicit push instructions such as push1 0x00 or push21 0x0000 will not be simplified to the PUSH0 opcode giving the developer full control over how they want their pushes to be compiled.

I had trouble getting some tests to pass, but it seems to be related to missing example files? Cloning the original stage branch already did not work. With the exception of the -p huff_codegen --doc target, not sure how to fix that.

My first Huff and generally Rust PR so feedback on coding / PR style is greatly appreciated! Thx!

[Maddiaa0]

Ah very nicely done @Philogy, excellent work especially if its your first rust work!!! Got a small note in the review section but overall i like the approach nicely done!

side note: ive made a branch that fixes the doc tests and erc20 tests here md/fix-doc-tests
Feel free to merge this branch into this pr and then ill get it merged

[clabby]

I'm a fan of setting this as the default, would also be awesome to have EVM versions in Huff to branch on the version devs are deploying on for things like this. Cool to merge on my end if there's consensus around doing this prior to the compiler handling separate hardforks / conditional codegen. cc @jtriley-eth @Maddiaa0

[Maddiaa0]

I'm a fan of setting this as the default, would also be awesome to have EVM versions in Huff to branch on the version devs are deploying on for things like this. Cool to merge on my end if there's consensus around doing this prior to the compiler handling separate hardforks / conditional codegen. cc @jtriley-eth @Maddiaa0

#281 have a pr here to trigger optional codegen