Standardize on syntax highlight organization and formatting

[brettcannon]

The language spec for test output lives entirely in syntaxes/ and is specified using the .tmLanguage format. The pip requirements file is spread out between syntaxes/ and languages/ and is defined using the JSON version of the .tmLanguages spec. The pip requirements files should be brought in line by consolidating all of the files into syntaxes/ and moving over to the XML format.

[DonJayamanne]

Brett Cannon (@brettcannon) the test.tmLanguage is not used, will remove that.
Also, vscode seems to have a mixture of json and xml formats, so I'd be inclined to leave the format as is.