Clickable images feature needs a global opt-out in docfx.json

[glopesdev]

As described in #8518 (comment).

The introduction of clickable images has been introducing several unpredictable behaviors to our DOM manipulation workflows. I'm not sure I understand the aim of this feature, and having an arbitrary cutoff of 200 pixels and no ability to opt-out is making us have to deal with unexpected edge cases.

Would be great to have a way to opt-out at the level of the docfx.json either with a flag (preferred) or by allowing to specify the value of the pixel cutoff (setting it to None or zero should probably disable the behavior).