Issue Type: Bug

We are developing an extension that implements a source control provider. It successfully adds SourceControlResourceGroups to its section. However the standard themes display the group captions in UPPERCASE by styling them with text-transform: uppercase

For our use case it's important to show the group captions in their actual case. AFAIK there isn't a way for our extension to make that happen.

VS Code version: Code 1.34.0 (a622c65, 2019-05-15T21:59:37.030Z)
OS version: Windows_NT x64 10.0.16299