memory: rename format_mem and format_swap to fromat and format_alt

[madhur]

Fixes issue #1642

[MaxVerevkin]

Memtype type can be removed.

[MaxVerevkin]

Please run rustfmt --edition 2021 src/blocks/memory.rs. Apparently cargo fmt (and cargo fmt --check) doesn't work on blocks' files because their mod <module> is defined inside of a macro. This is a known limitation of cargo fmt: rust-lang/rustfmt#4078

@ammgws I guess the CI should run something like rustfmt --check --edition 2021 $(fd -e rs) instead of cargo fmt --check?

[MaxVerevkin]

Please update the docs on lines 9-10

[MaxVerevkin]

Thanks!