Fixes #17453

This PR adds the abbility to block a user from a personal account or
organization to restrict how the blocked user can interact with the
blocker. The docs explain what's the consequence of blocking a user.

Screenshots:


![grafik](https://github.com/go-gitea/gitea/assets/1666336/4ed884f3-e06a-4862-afd3-3b8aa2488dc6)


![grafik](https://github.com/go-gitea/gitea/assets/1666336/ae6d4981-f252-4f50-a429-04f0f9f1cdf1)


![grafik](https://github.com/go-gitea/gitea/assets/1666336/ca153599-5b0f-4b4a-90fe-18bdfd6f0b6b)

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Co-authored-by: Lauris BH <lauris@nix.lv>

Fix #14459

The following users can add/remove review requests of a PR
- the poster of the PR
- the owner or collaborators of the repository
- members with read permission on the pull requests unit

* Add fixture gen tool and fix "access" test

* Close file before exiting

* Add missing repo_unit for repo id: 5

* Fix count on TestAPIOrgRepos

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

* Restricted users (#4334): initial implementation

* Add User.IsRestricted & UI to edit it

* Pass user object instead of user id to places where IsRestricted flag matters

* Restricted users: maintain access rows for all referenced repos (incl public)

* Take logged in user & IsRestricted flag into account in org/repo listings, searches and accesses

* Add basic repo access tests for restricted users

Signed-off-by: Manush Dodunekov <manush@stendahls.se>

* Mention restricted users in the faq

Signed-off-by: Manush Dodunekov <manush@stendahls.se>

* Revert unnecessary change `.isUserPartOfOrg` -> `.IsUserPartOfOrg`

Signed-off-by: Manush Dodunekov <manush@stendahls.se>

* Remove unnecessary `org.IsOrganization()` call

Signed-off-by: Manush Dodunekov <manush@stendahls.se>

* Revert to an `int64` keyed `accessMap`

* Add type `userAccess`
* Add convenience func updateUserAccess()
* Turn accessMap into a `map[int64]userAccess`

Signed-off-by: Manush Dodunekov <manush@stendahls.se>

* or even better: `map[int64]*userAccess`

* updateUserAccess(): use tighter syntax as suggested by lafriks

* even tighter

* Avoid extra loop

* Don't disclose limited orgs to unauthenticated users

* Don't assume block only applies to orgs

* Use an array of `VisibleType` for filtering

* fix yet another thinko

* Ok - no need for u

* Revert "Ok - no need for u"

This reverts commit 5c3e886aab.

Co-authored-by: Antoine GIRARD <sapk@users.noreply.github.com>
Co-authored-by: Lauris BH <lauris@nix.lv>

Handle case where an orginization is private but a user who is not a
member of the orgninization has been added as a collaborator of a repo
within that org

Fixes #6962