Feature-request: default to insert mode as an alternative to disabling

Currently users can maintain a list of websites on which vimium should be disabled entirely.

I only enable this when the websites themselves make heavy use of keyboard shortcuts by default. If instead I could ask vimium to start in insert mode on these websites, then I could just press escape and retain vimium's functionality too.

This kind of workflow is also hindered because after entering insert mode, interacting with the page using mouse (e.g. form controls) takes you out of the insert mode. If the user could stay in insert mode until esc was pressed, that'd make it better.

Start by tracing the existing website disable-list setting and the insert-mode handling described in the issue. Check how mouse interaction currently exits insert mode and identify the relevant browser-extension entry points. Done means the requested per-site default insert behavior and escape-based exit are defined and covered by appropriate tests.