Insert mode's <C-o> doesn't work properly

[turara]

Describe the bug
When you invoke a command that turns the mode to "Insert" after you invoke <C-o> in Insert mode (CommandOneNormalCommandInInsertMode), <Esc>/<C-o> won't turn the mode to "Normal".

To Reproduce
Steps to reproduce the behavior:

1. Go to Insert mode
2. Type <C-o>
3. Type o, A, I, or any command that turns the mode to "Insert"
4. Type some words
5. Type <Esc> or <C-o>
6. You are still in the Insert mode

Expected behavior
You go back to the Normal mode

Environment (please complete the following information):

• Extension (VsCodeVim) version: 1.11.2
• VSCode version: 1.38.1
• OS: macOS 10.14.6

Additional context

Related to #3074

Cause of the problem

I believe the following line is part of the cause although I couldn't figure out how to fix it.

Vim/src/mode/modeHandler.ts

Line 546 in 2f4c187

ranAction = ranAction && vimState.currentMode === ModeName.Normal;

When you type "o" after <C-o>, ranAction will be false because vimState.currentMode is ModeName.Insert and vimState.returnToInsertAfterCommand won't turn to false (Step 2 and 3). Then when you type <Esc> (Step 5),

1. CommandEscInsertMode.exec turns the mode to "Normal" (inside ModeHandler.runAction)
2. ModeHandler.runAction turns the mode back to "Insert" immediately.

[turara]

Seems fixed in #4461