Replace `get_` methods with `derive_getters::Getters` lib

[lorenzoberts]

Context:

The rust library derive_getters allows automatic creation of getter methods, by using a #[derive(Getters)] above the target struct.

Proposal:

• Use this lib and replace the existing get_ methods with the #[derive(Getters)]

  Setup:

• Project branch: unstable

• Project commit hash: 7379a9af52b2b84018d1a6b8916ad44c25cc2a35

• rustc version: rustc 1.80.1 (3f5fd8dd4 2024-08-06)

• cargo version: cargo 1.80.1 (376290515 2024-07-16)