Support `targets.vim` plugin

One plugin that is very useful for my VIM flow is this one:
https://github.com/wellle/targets.vim

It builds on the idea of the ci" command - where it jumps forward to find the nearest quotation, and changes inside, for other characters, like (), {}, [], etc.

It also supports argument text objects - which are handy for deleting and changing in function arguments. So cia would jump forward to an argument and change.

These motions and text objects are nice because they mean you can strike from a distance.

In terms of integration, it seems like it depends on whether the plugin story for this is implemented:
https://github.com/VSCodeVim/Vim/issues/590

If that happens, we might want to look at making the text objects extensible to support these scenarios.
Otherwise, we could potentially bake it in as a setting.

Note that ci" is already supported in VSCodeVim (and VIM out of the box), so potentially the work at least for those jump commands might not be too bad.

Start by reading the linked plugin issue, VSCodeVim/Vim#590, to determine whether extensible plugin support exists, then compare that with the current implementation of the existing ci" text object. Done means deciding and implementing support for the requested targets.vim motions and argument text objects, either through the plugin mechanism or a setting.