Move cmd start escape to end of prompt

[grgar]

#185907 moves the cmd start escape to the end of the mode prompt, but since the mode prompt ‘appears to the left of the regular prompt’ that seems too early: declaring that the start of the cmd causes the rest of the prompt to be part of the command in the recent commands list.

Moves __vsc_fish_cmd_start to the end of fish_prompt so the prompt is not part of the command. Tested that the prompt no longer appears in the recent commands and running the command from the recent list no longer tries to execute the prompt as the command.

[grgar]

Seems to be a more recent issue than #185907, implying #209946 is what actually broke it? Appears that before #209946, escape E was successfully specifying the command, but now C is before E the E no longer takes effect. However disregarding the change to E, #185907 still needs fixing in my opinion to place C in the right place. @Tyriar what testing steps took place for #209946 that I can use to reproduce what swapping the ordering of C and E did (when fish_mode_prompt is defined)?

[Tyriar]

@grgar the swapping of C and E makes the full command line available to the upcoming shellIntegration extension API. You can test it by uncommenting this part and then inspect the event object in devtools:

https://github.com/grgars/vscode/blob/25a72f2d208e1fa5408606693308e581f9bc6be5/src/vs/workbench/api/common/extHostTerminalShellIntegration.ts#L61-L73

It should show the correct command line with a confidence of 2.

I didn't do much testing outside of powershell and I tried just now to add a fish mode prompt but I don't think I could get it working. So if you can verify that your proposal works then we're good to merge 👌

[grgar]

Thanks @Tyriar, that was indeed very convenient test code!
Used that code to test before and after, now works with a fish_mode_prompt (as did trying recent commands previously):

Much appreciated showing me these additional test steps and thanks for merging.

[Tyriar]

@grgar awesome! Thanks a lot for the contribution