feat: add scenario labels

[0xl3on]

Motivation

Closes stale issue at #436

Solution

• Contract names are suffixed with _{label} when stored during deploy (insert_named_txs) and when looked up during template resolution (get_named_tx).
• Added scenario_label: Option to TestScenarioParams and TestScenario
• Added get_scenario_label() to the Generator trait
• Threaded scenario_label into Templater methods (find_placeholder_values, find_fncall_placeholders, find_create_placeholders) and DeployContractParams
• Exposed scenario_label on ContenderCtxBuilder for library users

PR Checklist

• Added Tests
• Added Documentation
• Ran cargo +nightly clippy --workspace --lib --examples --tests --benches --all-features --locked --fix
• Ran cargo fmt --all
• Note breaking changes in PR description, if applicable
• update changelogs
  • Update CHANGELOG.md in each affected crate
  • add a high-level description in the root changelog

[0xl3on]

Hey @zeroXbrock !

Noticed that this issue was stale for a long time so picked it up. Hope that's fine!