Adding sensitivity maps for forward models in mne.report

[1himan]

Reference issue (if any)

Fixes #2828.

What does this implement/fix?

now the report looks something like this:

[tsbinns]

@1himan Just FYI, the :meth: formatting was recently fixed here: #13690
In the first screenshot, you are looking at the stable documentation where this has not been fixed, but if you look at the dev docs online or in your second screenshot, it is fixed (regardless of the newline change).

[1himan]

@1himan Just FYI, the :meth: formatting was recently fixed here: #13690 In the first screenshot, you are looking at the stable documentation where this has not been fixed, but if you look at the dev docs online or in your second screenshot, it is fixed (regardless of the newline change).

nice. I'll change accordingly.

[larsoner]

Don't forget doc/changes/13722.newfeature.rst as well