## Summary of the Pull Request
This PR causes the Terminal to combine taskbar states at the tab and window level, according to the [MSDN docs for `SetProgressState`](https://docs.microsoft.com/en-us/windows/win32/api/shobjidl_core/nf-shobjidl_core-itaskbarlist3-setprogressstate#how-the-taskbar-button-chooses-the-progress-indicator-for-a-group).
This allows the Terminal's taskbar icon to continue showing progress information, even if you're in a pane/tab that _doesn't_ have progress state. This is helpful for cases where the user may be running a build in one tab, and working on something else in another.
## References
* [`SetProgressState`](https://docs.microsoft.com/en-us/windows/win32/api/shobjidl_core/nf-shobjidl_core-itaskbarlist3-setprogressstate#how-the-taskbar-button-chooses-the-progress-indicator-for-a-group)
* Progress mega: #6700
## PR Checklist
* [x] Closes#10090
* [x] I work here
* [ ] Tests added/passed
* [n/a] Requires documentation to be updated
## Detailed Description of the Pull Request / Additional comments
This also fixes a related bug where transitioning from the "error" or "warning" state directly to the "indeterminate" state would cause the taskbar icon to get stuck in a bad state.
## Validation Steps Performed
<details>
<summary><code>progress.cmd</code></summary>
```cmd
@echo off
setlocal enabledelayedexpansion
set _type=3
if (%1) == () (
set _type=3
) else (
set _type=%1
)
if (%_type%) == (0) (
<NUL set /p =]9;4
echo Cleared progress
)
if (%_type%) == (1) (
<NUL set /p =]9;4;1;25
echo Started progress (normal, 25^)
)
if (%_type%) == (2) (
<NUL set /p =]9;4;2;50
echo Started progress (error, 50^)
)
if (%_type%) == (3) (
@rem start indeterminate progress in the taskbar
@rem this `<NUL set /p =` magic will output the text _without a newline_
<NUL set /p =]9;4;3
echo Started progress (indeterminate, {omitted})
)
if (%_type%) == (4) (
<NUL set /p =]9;4;4;75
echo Started progress (warning, 75^)
)
```
</details>
a14b6f89f6
