Named shared pages

Description

In case if we would like to have a nice url instead uuid we could use share name as url.
If link is mean to be public url and could be shared with anyone then we can make this url more friendly.

Users will be capable of having:
https://jira.external-share.com/issue/q4-2021-external-share-roadmap instead of
https://jira.external-share.com/issue/c6c6ac22-b102-4244-8468-673b0cc83a96

We have to figure out strategy to ensure there will be no collision in names.