Problem switching in and out of UTF-8 mode

### Windows Terminal version

1.18.3181.0

### Windows build number

10.0.22621.0

### Other Software

_No response_

### Steps to reproduce

Output the character sequence twice using a tool of your choice:
`Esc % G E2 A3 BF Esc % @`

### Expected Behavior

Each time, the unicode character 28FF ⣿ (Braille Pattern Dots-12345678) will be printed.

### Actual Behavior

The correct character is printed the first time, the second time (and any subsequent times) prints "⣿".

From my reading of the code, this is because Esc % @ (Select Default Character Set) correctly disengages UTF-8 by calling DesignateCodingSystem in ActionCsiDispatch. However, its companion seuqnece Esc % G (Select UTF-8 Character Set) is not handled and thus the sequence is never again rendered in Unicode.

Start in the terminal escape-sequence handling around ActionCsiDispatch and DesignateCodingSystem, comparing the provided Esc % G and Esc % @ sequences. Reproduce the sequence twice and verify that the second output is ⣿ rather than mojibake.

Written by the indexing model from the issue text.