Improve new prefix form

[cthoyt]

• Activate the ability to add the contributor email
• Add field for publications
• Rename "Repository" to "Source Code Repository" to reduce confusion (people kept putting "bioregistry" as the value for this...)

[codecov[bot]]

Codecov Report

Attention: 13 lines in your changes are missing coverage. Please review.

Comparison is base (7daea25) 40.89% compared to head (0974a02) 40.82%.

Files	Patch %	Lines
src/bioregistry/gh/new_prefix.py	0.00%	13 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1000 +/- ## ========================================== - Coverage 40.89% 40.82% -0.07% ========================================== Files 138 138 Lines 7916 7928 +12 Branches 1845 1847 +2 ========================================== Hits 3237 3237 - Misses 4477 4489 +12 Partials 202 202 ```

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