Do not notify value changed when SetValue() is called from Streamlit script

[mikeprosserni]

What does this Pull Request accomplish?

If setting a value in a streamlit script sent the value update notification, the streamlit script would re-run, potentially setting the value again and causing an infinite loop. We need to prevent this by NOT notifying when StreamlitPanelValueAccessor.set_value() is called.

The SetValueRequest now includes a 'notify' flag. This flag is false when StreamlitPanelValueAccessor.set_value() is called, and is true when StreamlitPanel.set_value() is called.

Why should this Pull Request be merged?

Implements AB#3145075

What testing has been done?

Validated with a debugger that setting a value using StreamlitPanel in a measurement script triggers the _panelEventNotifier.NotifyPanelValueChanged(), but setting a value using StreamlitPanelValueAccessor in the streamlit script does not.

test___panel___set_value___notifies
test___accessor___set_value___does_not_notify

[github-actions]

Test Results

 10 files  ± 0   10 suites  ±0   10s ⏱️ -1s
 67 tests + 2   67 ✅ + 2  0 💤 ±0  0 ❌ ±0 
640 runs  +20  640 ✅ +20  0 💤 ±0  0 ❌ ±0 

Results for commit e5f741c. ± Comparison against base commit f5af8a9.