[Feature] Add serde helpers for handling maps with quantity keys

[mattsse]

Component

serde

Describe the feature you would like

we already have helpers for handling vec

alloy/crates/serde/src/quantity.rs

Lines 61 to 64 in 8857646

	/// Serde functions for encoding a list of primitive numbers using the Ethereum "quantity" format.
	///
	/// See [`quantity`](self) for more information.
	pub mod vec {

it can be useful to have the same for hashmaps/btreemaps with quantity key types

TODO

• add mods with manual map serde; take over this wip feat: quantity map serde #1503

Additional context

No response