test: add rstest and fixtures

[carlosvdr]

Added rstest:

• with this several tests have been refactored to only receive fixtures created on rstest

this PR aims to make the tests more easy reading and only focusing on the important bits per test

Due to the nature of async fixtures some tests could use them since the test itself needed to be in some order for it to work as intended.

[github-actions]

Pull Request Test Coverage Report for Build 13338777287

Details

• 58 of 62 (93.55%) changed or added relevant lines in 5 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.3%) to 75.527%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
crates/tap-agent/src/agent/sender_accounts_manager.rs	7	9	77.78%
crates/test-assets/src/lib.rs	29	31	93.55%

Files with Coverage Reduction	New Missed Lines	%
crates/tap-agent/src/agent/sender_account.rs	1	75.63%

Totals
Change from base Build 13317981472:	-0.3%
Covered Lines:	8237
Relevant Lines:	10906

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💛 - Coveralls