On Russian keyboards, "Б" character adds a tag

### Expected
We should split on commas regardless of keyboard layout

### Observed
On Russian keyboards, the "Б" character is apparently the same keycode as the comma on English keyboards so typing it causes a tag to be added.

It's possible this also implies that comma doesn't work to add a tag for Russian keyboards (since it would be a different keycode). I haven't tested that scenario.

User reported in 2896068-zen and reproduced it in Windows 10 and on web.

No file or test is named in the issue. Start by locating the tag-input keyboard handler and reproduce the behavior on Windows 10 with a Russian keyboard layout; done means commas add tags regardless of layout and typing Б does not add a tag.

Written by the indexing model from the issue text.