Ban unsafe arithmetic operations

[keithtensor]

Devnet Companion: #529

This PR bans raw arithmetic operations such as those with the + - / * symbols, and instead replaces them with either the saturating equivalent, or the checked equivalent.

Resolves #303.

[sam0x17]

looks like some conflicts + CI failures now @keithtensor

[sam0x17]

I had gpt 4o go over the diff of this in detail with me as well and it is satisfied all of these preserve the original behavior after a long convo

[distributedstatemachine]

Approved but lets wait for @sam0x17 on merging this

[sam0x17]

changes look good, next step would be for a companion PR to open, with a link to this branch, that merges a this branch into devnet-ready

[sam0x17]

So yeah again, should have a companion that merges this branch into devnet-ready. Not sure what this opentensor:development is or why people keep opening PRs into it 😕

[sam0x17]

but yeah if this is already tested on devnet, should add the devnet-pass label, if this is already tested on testnet, should add the testnet-pass label, at which point it should be able to merge into main

[Mananitade]

I'm curious about the outright ban of the operations + - / *, since these are rather common operations. Have you considered an alternative of catching overflow exceptions? To me, it seems like an overkill, but I'm open to being convinced otherwise. Is it considered good practice in the Rust community to ban these operations? What are the tradeoffs (how much slower does it make things run)?

[sam0x17]

I'm curious about the outright ban of the operations + - / *, since these are rather common operations. Have you considered an alternative of catching overflow exceptions? To me, it seems like an overkill, but I'm open to being convinced otherwise. Is it considered good practice in the Rust community to ban these operations? What are the tradeoffs (how much slower does it make things run)?

main reason being panicking in an extrinsic is enough to brick a substrate-based chain. On parity's end they have always said you should only use checked math in extrinsics.