Ban U256::as_u64 and similar functions

[gztensor]

Conversions like U256::as_u64 can panic if U256 value doesn't fit the bitness. We need to ban use of these functions and recommend replacing with try_into.

[sam0x17]

some context:

you will want to look at the custom linting framework in https://github.com/opentensor/subtensor/tree/devnet-ready/support/linting and write a custom lint that finds all .as_[primitive here] method calls and flags them as errors.

lints are run by running cargo check from the root of the repo. You do not need --workspace

you can enable the lint by adding it here: https://github.com/opentensor/subtensor/blob/devnet-ready/build.rs#L62-L63

[eagr]

I'll give it a shot :)

[sam0x17]

ok that is totally fine @eagr, there is also already another community working on it, maybe you two will work together. I will get back to you about that!

[eagr]

oops, I didn't know.. btw, I keep the checks to the conversion methods of U256 / U512 to minimize false lint errors. but lmk if that's too specific. is it just me or is nalgebra taking forever to build?

[sam0x17]

I keep the checks to the conversion methods of U256 / U512 to minimize false lint errors

that is ideal, excellent

[sam0x17]

completed in #846