[DSLX:LS] Ansi color codes don't render in vscode problems pane

**Describe the bug**
The dslx_ls produces ANSI escapes in the problems pane in VSCode.

**To Reproduce**
Install DSLX vscode extension
Point at dslx_ls installation
Make a type error where we're displaying member type diffs (e.g. a component within a tuple)
Observe the unredered ANSI escapes

**Expected behavior**
I think somehow other languages provide color coding? But if not we probably need to plumb a "can do ANSI escapes" from the outside world to the error rendering.

**Screenshots**