Add continuous acquisition examples for thrmcpl and digital trigger

[WayneDroid]

• [x] This contribution adheres to CONTRIBUTING.md.

What does this Pull Request accomplish?

• add continuous thrmcpl samples acquisition example.
• add digital start, digital start ref, digital start retrigger examples.

Why should this Pull Request be merged?

These AI examples are requested in the feature scope to be released in version 1.0.

What testing has been done?

run poetry run pytest tests/ -q - pass

Validated on physical device PXIe-6363 - okay

C:\dev\repo2\nidaqmx-python>poetry run python examples\analog_in\cont_thrmcpl_samples_int_clk.py       
Acquiring samples continuously. Press Ctrl+C to stop.
Acquired data: 1000 samples. Total 4000.
Acquired 4000 total samples.

C:\dev\repo2\nidaqmx-python>poetry run python examples\analog_in\cont_voltage_acq_int_clk_dig_start.py
Acquiring samples continuously. Press Enter to stop.
Acquired data: 1000 samples. Total 3000.

Acquired 3000 total samples.

C:\dev\repo2\nidaqmx-python>poetry run python examples\analog_in\voltage_acq_int_clk_dig_start_ref.py      
Acquired data: [0.721807, 0.721807, 0.722129, 0.722290, 0.721968, 0.721968, 0.721968, 0.721807, 0.721485, 0.721163, 0.721163, 0.721002, 0.720680, 0.720841, 0.720680, 0.720841, 0.720680, 0.720841, 0.721002, 0.721324, 0.721163, 0.721163, 0.721485, 0.721485, 0.721485, 0.721646, 0.721324, 0.721485, 0.721324, 0.720841, 0.720680, 0.720196, 0.720518, 0.720518, 0.720196, 0.720196, 0.720357, 0.720518, 0.721002, 0.721002, 0.720841, 0.721163, 0.721485, 0.721163, 0.721002, 0.721163, 0.720841, 0.721163, 0.721163, 0.720518, 0.720357, 0.720196, 0.720357, 0.720196, 0.720035, 0.719874, 0.720196, 0.720196, 0.720518, 0.720518, 0.720680, 0.720680, 0.720841, 0.720680, 0.721163, 0.721002, 0.721002, 0.720518, 0.720841, 0.720518, 0.720035, 0.720196, 0.719874, 0.719552, 0.719874, 0.719713, 0.720035, 0.719713, 0.720196, 0.720035, 0.720518, 0.720680, 0.720680, 0.720841, 0.720680, 0.720680, 0.720680, 0.720196, 0.720196, 0.720035, 0.720035, 0.719874, 0.719552, 0.719874, 0.719391, 0.719552, 0.719874, 0.719874, 0.720035, 0.720196]

C:\dev\repo2\nidaqmx-python>poetry run python examples\analog_in\cont_voltage_acq_int_clk_dig_start_retrig.py
Acquiring samples continuously. Press Enter to stop.
Acquired data: 1000 samples. Total 7000.

Acquired 7000 total samples.