TO BE DISCUSSED: Drop type of community/venue in favour of generic "collection"

[nuest]

This shortens the URLs and the type is better documented in JSON/HTML content. We also don't have to worry about a meaningful classification right now.

Before:

• https://codecheck.org.uk/register/venues/conference/AGILEGIS/
• https://codecheck.org.uk/register/venues/community/codecheck_NL/

After:

• https://codecheck.org.uk/register/collection/AGILEGIS/
• https://codecheck.org.uk/register/collection/NL/

[nuest]

We keep the type!