Improve account class testing

[FabijanC]

Usage related changes

• None

Development related changes

• Include cairo0 and cairo1 contract interaction in account class testing.
• Remove explicit providing of nonce and max_fee (now implicitly estimated), so that the util function can be reused between tests.
• Expand assert_tx_successful to include finality status assertion.
• Change the return value of the deploy_account util function to include the signer (needed in some test cases).
• Reduce line count by extracting BackgroundDevnet CLI args to a separate line.

Checklist:

• Checked out the contribution guidelines
• Applied formatting - ./scripts/format.sh
• No linter errors - ./scripts/clippy_check.sh
• No unused dependencies - ./scripts/check_unused_deps.sh
• No spelling errors - ./scripts/check_spelling.sh
• Performed code self-review
• Rebased to the latest commit of the target branch (or merged it into my branch)
• Updated the docs if needed - ./website/README.md
• Linked the issues resolvable by this PR - linking info
• Updated the tests if needed; all passing - execution info