## Summary of the Pull Request
This PR reverses the behaviour of the `IS_GLYPH_CHAR` macro, so it now actually returns true if the given char is a glyph, and false if it isn't. Previously it returned the opposite of that, which meant it had to be called as `!IS_GLYPH_CHAR` to get the correct result.
## PR Checklist
* [x] Closes#4185
* [x] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [ ] Tests added/passed
* [ ] Requires documentation to be updated
* [x] I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #4185
## Detailed Description of the Pull Request / Additional comments
The original implementation returned true if the given character was a C0 control, or a DEL:
#define IS_GLYPH_CHAR(wch) (((wch) < L' ') || ((wch) == 0x007F))
It's now the exact opposite, so returns true for characters that are _not_ C0 controls, and are not the DEL character either:
#define IS_GLYPH_CHAR(wch) (((wch) >= L' ') && ((wch) != 0x007F))
The macro was only used in one place, where is was being called as `!IS_GLYPH_CHAR` when the intent was actually to test whether the char _was_ a glyph. That code could now be updated to remove the `!`, so it makes more sense.
## Validation Steps Performed
I've just tested manually and confirmed that basic output of text and control chars still worked as expected in a conhost shell.
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