Enable emulation testing with pytest-xdist support

[tfcollins]

Add pytest-xdist support for emulation testing in CI

[github-actions]

Test Results

1 612 tests  ±0      15 ✅  - 349   1m 5s ⏱️ - 10m 28s
    1 suites ±0   1 250 💤 +  2 
    1 files   ±0     347 ❌ +347 

For more details on these failures, see this check.

Results for commit 79097f9. ± Comparison against base commit 191e31d.

This pull request skips 6 and un-skips 4 tests.

test.test_adrv9002_generic_p ‑ test_iio_attr[channel-adrv9002-phy-altvoltage0-True-frequency-70000000-6000000000-1-4-100]
test.test_adrv9002_generic_p ‑ test_iio_attr[channel-adrv9002-phy-altvoltage1-True-frequency-70000000-6000000000-1-4-100]
test.test_adrv9002_generic_p ‑ test_iio_attr[channel-adrv9002-phy-voltage0-False-hardwaregain--89.75-0.0-0.25-0-100]
test.test_generic ‑ test_iio_attr[channel-ad9361-phy-RX_LO-True-frequency-70000000-6000000000-1-4-100]
test.test_generic ‑ test_iio_attr[channel-ad9361-phy-TX_LO-True-frequency-47000000-6000000000-1-4-100]
test.test_generic ‑ test_iio_attr[channel-ad9361-phy-voltage0-False-hardwaregain--89.75-0.0-0.25-0-100]

test.test_adrv9002_p ‑ test_adrv9002_interface_gain_narrowband[interface_gain_chan0-val0-depends0-adi.adrv9002]
test.test_adrv9002_p ‑ test_adrv9002_interface_gain_narrowband[interface_gain_chan1-val1-depends1-adi.adrv9002]
test.test_adrv9002_p ‑ test_adrv9002_tx_data[True-0-adi.adrv9002]
test.test_adrv9002_p ‑ test_adrv9002_tx_data[True-1-adi.adrv9002]

♻️ This comment has been updated with latest results.

[github-actions]

Generated documentation for this PR is available at Link