Character count in addition to word and line counts

It would be great to be able to show the character count, not only words and lines. Character counts are helpful to meet a fields min or max character validation.

No file or test is named. Start by locating the existing word and line count implementation and its tests, then determine where the character count should be displayed alongside them. Done means the editor shows character counts in addition to word and line counts and the behavior is covered by the relevant tests.

Written by the indexing model from the issue text.