Ensure that extension inherits core python activation settings

[karthiknadig]

Looks like in some cases the extension is defaulting to command even though core extension is set to activation off.

These settings:
python.terminal.activateEnvInCurrentTerminal
python.terminal.activateEnvironment

[anthonykim1]

@karthiknadig Right now we do respect python.terminal.activateEnvironment setting. This is default true, so if we see that this is false, we change the autoActivation type to off, and command (default atm) otherwise.

python.terminal.activateEnvInCurrentTerminal is the tricky one. It has no effect when env extension is enabled.

EDIT: Respect the value of python.terminal.activateEnvInCurrentTerminal if ONLY it is explicitly set to false.
#1318

[vs-code-engineering]

Sharing image/GIF media from merged PR #1318 for verification:

explicitFalse.mov

explicittrueorrDefault.mov

Source PR: #1318