[Notts Police] Prevent reports being made if they contain email

[MorayMySoc]

Checks report for email address and returns error requesting removal if found in title or detail. Fixes https://github.com/mysociety/societyworks/issues/4338

Also moves Highways England code regex match into Utils for general use.

[skip changelog]

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 82.60%. Comparing base (0c49d46) to head (842a468).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## notts-police-reviewed #5008 +/- ## ========================================================= + Coverage 82.55% 82.60% +0.04% ========================================================= Files 394 394 Lines 30771 30778 +7 Branches 4878 4879 +1 ========================================================= + Hits 25404 25423 +19 + Misses 3915 3902 -13 - Partials 1452 1453 +1 ```

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