Makes MantidPlot opt-in for new CMake generations. At the point of
writing the CI jobs have been building with MantidPlot disabled fine for
a while.

Make it so that any new CMake build directories have it off by default,
so people can opt-in if they really need it. Note this does not impact
existing CMakeCaches, so someone with Plot on will continue to have it
on.

Return shared_pointer in Python WorkspaceGroup.getItem()

Fix handling image replotting when the underlying workspace updates

Added unit test to test findContainer without specified ID

Handles if norm is passed to the creation of the original plot
like is done in the mantidqt widgets layer

Python output 29987

Create Python StdoutChannel

Refs #29987

and add documentation about the feature. Refs #29987

Refs #29987

There is still something not quite right with the library linking. The
new channel isn't in the library at time of initialization.

Refs #29987

Refs #29987

Refs #29987

Gigg, Martyn Anthony authored Nov 25, 2020 and Peterson, Peter committed Dec 07, 2020

This allows a package build to only include
workbench/mantidplot depending on the cmake
flags that are set.

Martyn Gigg authored Nov 05, 2020 and Peterson, Peter committed Dec 07, 2020

Linux profile scripts now only include PV_PLUGIN_PATH
if Vates is built