Add io_jitter and io_delay modes to GUI

[gavv]

In --mode io_jitter and --mode io_delay, CLI tool measures jitter of I/O operations, ALSA ring buffer size, and hardware delay reported by ALSA, and periodically prints average and 95th percentile values. See docs: https://github.com/gavv/signal-estimator#measuring-io-jitter-and-delay

GUI already has options for io_jitter and io_delay in Options tab, but does not yet allow to run measurement in this mode.

What we need to do:

• add parsing of io_jitter and io_delay reports to SignalEstimator class (currently GUI runs CLI tool and parses reports from its stdout)

• add io_jitter and io_delay to Mode combobox

• handle io_jitter and io_delay modes in MainWindow class: display last report and add reports to plots

This screenshot shows what parts depend on measurement mode and thus need to be updated:

[Ajay-26]

Hi, I would like to contribute to this issue.