we need some way to search the text of issues and comments

Is this a normal filter?  Maybe `ent list text=REGEX`?

Or maybe we want more detailed output than just a list?  Showing the
actual Issue or Comment that matches.  Maybe `ent search REGEX` producing
something like:
```
$ ent search REGEX
issue: issue1
blah blah

issue: issue2
blah
    comment 1
    comment 2
```