waveform: Add support for complex waveforms

[bkeryan]

• This contribution adheres to CONTRIBUTING.md.

What does this Pull Request accomplish?

Create the ComplexWaveform class to support complex-number waveforms:

• Extract most of AnalogWaveform into an abstract base class, NumericWaveform (as opposed to DigitalWaveform)
• Rename existing type variable to _TRaw_co
• Add a second type variable to NumericWaveform, _TScaled_co. For AnalogWaveform, _TScaled_co=np.float64 and for ComplexWaveform, _TScaled_co=np.complex128.
• Add an abstract helper method to handle ComplexInt32DType conversion.

Why should this Pull Request be merged?

Closes AB#3066698 - Define Python complex waveform data types

What testing has been done?

Ran poetry run nps lint, mypy, pytest -v

[github-actions]

Test Results

   10 files  ±  0     10 suites  ±0   30s ⏱️ +3s
  573 tests + 41    573 ✅ + 41  0 💤 ±0  0 ❌ ±0 
5 730 runs  +410  5 730 ✅ +410  0 💤 ±0  0 ❌ ±0 

Results for commit eaa1342. ± Comparison against base commit b20757f.

This pull request removes 1 and adds 42 tests. Note that renamed tests count towards both.

tests.unit.waveform.test_analog_waveform ‑ test___sample_count_and_unsupported_dtype___create___raises_type_error

tests.unit.complex.test_dtypes ‑ test___duplicate_structured_dtype___equality___equal
tests.unit.complex.test_dtypes ‑ test___structured_dtype_str___equality___not_equal
tests.unit.complex.test_dtypes ‑ test___unknown_structured_dtype___equality___not_equal
tests.unit.waveform._scaling.test_linear ‑ test___complex128_ndarray___transform_data___returns_complex128_scaled_data
tests.unit.waveform._scaling.test_linear ‑ test___complex64_ndarray___transform_data___returns_complex64_scaled_data
tests.unit.waveform._scaling.test_none ‑ test___complex128_ndarray___transform_data___returns_complex128_scaled_data
tests.unit.waveform._scaling.test_none ‑ test___complex64_ndarray___transform_data___returns_complex64_scaled_data
tests.unit.waveform.test_analog_waveform ‑ test___dtype_str_with_traw_hint___create___narrows_traw
tests.unit.waveform.test_analog_waveform ‑ test___dtype_str_with_unsupported_traw_hint___create___mypy_type_var_warning
tests.unit.waveform.test_analog_waveform ‑ test___sample_count_and_unsupported_dtype___create___raises_type_error[complex128]
…

♻️ This comment has been updated with latest results.