[FEATURE] Add console block highlight

[alexminder]

Is your feature request related to a problem? Please describe.

There no code highlight for console content. Bash,shell and console is not the same.

Describe the solution you'd like

For example, Github render engine supports console block identifier:

```console
foo@bar:~$ whoami
foo
```

It listed in https://github.com/github-linguist/linguist/blob/master/lib/linguist/languages.yml#L6782

[pbek]

The code block highlighting is part of https://github.com/pbek/qmarkdowntextedit.

You could look at the bash highlighting and use that as a starting point:
https://github.com/pbek/qmarkdowntextedit/blob/48d602b174ac5f6600149b3874b00a01553bda94/markdownhighlighter.cpp#L336

The last language contribution was this commit, it could also serve as a good example of what to do:
pbek/qmarkdowntextedit@8157cd6