Other options for overriding profile starting directory

Description of the new feature/enhancement

The new command line arg for specifying starting directory is great but it's limited to individual panes and tabs created during launch. I'd like additional ways of specifying starting directories for panes/tabs, particularly those that get created after launch. Here's two additions I think would be useful:

Window-wide starting directory command line argument

Starting a terminal with wt --windowStartingDirectory "c:\my\project\dir" would cause all tabs/panes opened during the life of that terminal window to start in c:\my\project\dir. This is useful for opening a terminal window directly in a deeply nested project directory and then quickly and easily opening/closing additional panes/tabs in that location. This should also apply to all panes/tabs created via initial command line args that don't have an individual --startingDirectory specified.

You can more or less achieve this right now by setting a profile's starting directory to . and starting wt.exe itself with the actual desired starting directory as working directory. However this requires a more complicated launch, eg. cmd /C start /D "c:\my\project\dir" wt. You also lose the ability to keep a useful default starting directory in the profile's settings for a simple launch of wt.exe.

newTab and splitPane keybind options for reusing current directory

An additional option for the newTab/splitPane keybindings could open these with starting directory set to the current working directory of the current tab/pane. Useful if you open a terminal, eventually cd to some directory, and then want additional panes/tabs in that directory.

These would be additions to a prioritized list where the tab/pane being created uses the highest priority starting directory that was provided, eg:

1. reuse current directory via keybind
2. --startingDirectory command line argument
3. --windowStartingDirectory command line argument
4. profile starting directory
5. wt.exe working directory

Start by tracing the existing --startingDirectory handling and the newTab and splitPane keybinding paths. Done means supporting a window-wide fallback and current-directory reuse while preserving the stated priority order for all newly created tabs and panes.