External frontend url

[vuorioma]

Checklist for author

#3402

• Added the :external-frontend-url configuration option. This is used to override the url in outbound emails for use cases where REMS is used in conjuction with an external frontend application.

Remove items that aren't applicable, check items that are done.

Reviewability

• Link to issue
• Note if PR is on top of other PR
• Note if related change in rems-deploy repo
• Consider adding screenshots for ease of review

Backwards compatibility

• API is backwards compatible or completely new
• Events are backwards compatible or have migrations
• Config is backwards compatible
• Feature appears correctly in PDF print

Documentation

• Update changelog if necessary
• API is documented and shows up in Swagger UI
• Components are added to guide page
• Update docs/ (if applicable)
• Update manual/ (if applicable)
• ADR for major architectural decisions or experiments
• New config options in config-defaults.edn

Testing

• Complex logic is unit tested
• Valuable features are integration / browser / acceptance tested automatically

Follow-up

• New tasks are created for pending or remaining tasks

[pikariop]

Ran the changes locally, seems to work. The config key should be added to resources/config-defaults.edn to avoid a warning on startup. Ready to merge once the checklist is updated and the new key is present in config-defaults.edn.

[pikariop]

Perhaps we could call this function

Suggested change

	(defn url [] (or (not-empty (:external-frontend-url env)) (:public-url env)))
	(defn base-url [] (or (not-empty (:external-frontend-url env)) (:public-url env)))

to be a bit more specific