service: Update reserve_session(s) to accept a single pin and explicitly specify default timeout

[bkeryan]

• This contribution adheres to CONTRIBUTING.md.

What does this Pull Request accomplish?

SessionManagementClient:

• Update reserve_session(s) to accept a single pin for the pin_or_relay_names argument.
• Change reserve_session(s) and reserve_all_registered_sessions to explicitly specify a default timeout of 0.0.
• Change timeout handling to raise a RuntimeWarning when you specify a negative timeout other than -1, such as timeout=-2 or timeout=-1e6. This maintains compatibility with the existing behavior, but encourages clients to use -1 for an infinite timeout.
• Update documentation.
• Add more unit test cases.

Why should this Pull Request be merged?

Accepting a single pin allows calling reserve_session(context, "Vdd") without wrapping the pin name in a list or tuple.

In Python, str is a Iterable[str] that iterates over the characters of the string. Before this change, reserve_session(context, "Vdd") would pass type checking, but at run time it translated "Vdd" to ["V", "d", "d"], which is surprising behavior.

The default timeout behavior was previously undocumented. Using a default value of None was ambiguous, because None could plausibly be interpreted as either -1 (infinite) or 0.0 (non-blocking).

What testing has been done?

Ran poetry run pytest -v.
Manually tested a modified version of nidmm_measurement.
Ran poetry run sphinx-build _docs_source docs -b html -W --keep-going and looked at the output.

[github-actions]

Test Results

     12 files  ±    0       12 suites  ±0   2m 21s ⏱️ +19s
   215 tests +  17     186 ✔️ +  17    29 💤 ±0  0 ❌ ±0 
2 568 runs  +204  2 220 ✔️ +204  348 💤 ±0  0 ❌ ±0 

Results for commit d5b70fa. ± Comparison against base commit ceda75a.

This pull request removes 3 and adds 20 tests. Note that renamed tests count towards both.

tests.unit.test_session_management ‑ test___reserve_all_registered_sessions___sends_request
tests.unit.test_session_management ‑ test___reserve_session___sends_request
tests.unit.test_session_management ‑ test___reserve_sessions___sends_request

tests.unit.test_session_management ‑ test___all_optional_args___reserve_all_registered_sessions___sends_request_with_args
tests.unit.test_session_management ‑ test___all_optional_args___reserve_session___sends_request_with_args
tests.unit.test_session_management ‑ test___all_optional_args___reserve_sessions___sends_request_with_args
tests.unit.test_session_management ‑ test___explicit_none___reserve_all_registered_sessions___sends_request_with_defaults
tests.unit.test_session_management ‑ test___explicit_none___reserve_session___sends_request_with_defaults
tests.unit.test_session_management ‑ test___explicit_none___reserve_sessions___sends_request_with_defaults
tests.unit.test_session_management ‑ test___infinite_timeout___reserve_all_registered_sessions___sends_request_with_infinite_timeout[-1.0]
tests.unit.test_session_management ‑ test___infinite_timeout___reserve_all_registered_sessions___sends_request_with_infinite_timeout[-1]
tests.unit.test_session_management ‑ test___infinite_timeout___reserve_session___sends_request_with_infinite_timeout[-1.0]
tests.unit.test_session_management ‑ test___infinite_timeout___reserve_session___sends_request_with_infinite_timeout[-1]
…

♻️ This comment has been updated with latest results.