vim: Add support for temporary normal mode (ctrl-o) within insert mode (#19454)

Support has been added for the ctrl-o command within insert mode. Ctrl-o
is used to partially enter normal mode for 1 motion to then return back
into insert mode.

Release Notes:

- vim: Added support for `ctrl-o` in insert mode to enter temporary
normal mode

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/vim/test_data/test_ctrl_o_dot.json

@@ -0,0 +1,11 @@
+{"Put":{"state":"heˇllo world."}}
+{"Key":"x"}
+{"Key":"i"}
+{"Key":"ctrl-o"}
+{"Key":"."}
+{"Get":{"state":"heˇo world.","mode":"Insert"}}
+{"Key":"l"}
+{"Key":"l"}
+{"Key":"escape"}
+{"Key":"."}
+{"Get":{"state":"hellˇllo world.","mode":"Normal"}}