This commit adds release notes detailing the change of output names from Polaris.create_total_scattering_pdf

re: #28414

This commit adds lines in generate_ts_pdf to change the names of the workspaces produced as a result from the function.

re: #28414

Fixes all flake8 3.7.9 warnings as part of the Python 2->3 transition.

Co-Authored-By: Harrietbrown <49688535+Harrietbrown@users.noreply.github.com>

Co-Authored-By: Harrietbrown <49688535+Harrietbrown@users.noreply.github.com>

The autoscaling is now applied when truly necessary.

Re #28243

Skips any missing ws spectra whilst masking. This can happen if a user
crops to a component, causing sepctra gaps between banks.
We now filter any spectrum numbers not in the WS and emit a warning to
the user when this happens

This is required to still automatically select mode when the chopper frequency may have spin up/down values

Modified the navigation toolbar to allow for custom options, including Show/hide legend.