Allow non-admin users to delete review requests (#29057)

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

(cherry picked from commit c42083a33950be6ee9f822c6d0de3c3a79d1f51b)

Conflicts:
	models/repo/repo_list_test.go
	tests/integration/api_nodeinfo_test.go
	tests/integration/api_repo_test.go
	shared fixture counts

tests/gitea-repositories-meta/org41/repo61.git/HEAD

@@ -0,0 +1 @@
+ref: refs/heads/master

tests/gitea-repositories-meta/org41/repo61.git/config

@@ -0,0 +1,6 @@
+[core]
+	repositoryformatversion = 0
+	filemode = false
+	bare = true
+	symlinks = false
+	ignorecase = true

tests/gitea-repositories-meta/org41/repo61.git/description

@@ -0,0 +1 @@
+Unnamed repository; edit this file 'description' to name the repository.

tests/gitea-repositories-meta/org41/repo61.git/info/exclude

@@ -0,0 +1,6 @@
+# git ls-files --others --exclude-from=.git/info/exclude
+# Lines that start with '#' are comments.
+# For a project mostly in C, the following would be a good set of
+# exclude patterns (uncomment them if you want to use them):
+# *.[oa]
+# *~

tests/gitea-repositories-meta/user40/repo60.git/HEAD

@@ -0,0 +1 @@
+ref: refs/heads/master

tests/gitea-repositories-meta/user40/repo60.git/config

@@ -0,0 +1,6 @@
+[core]
+	repositoryformatversion = 0
+	filemode = false
+	bare = true
+	symlinks = false
+	ignorecase = true

tests/gitea-repositories-meta/user40/repo60.git/description

@@ -0,0 +1 @@
+Unnamed repository; edit this file 'description' to name the repository.

tests/gitea-repositories-meta/user40/repo60.git/info/exclude

@@ -0,0 +1,6 @@
+# git ls-files --others --exclude-from=.git/info/exclude
+# Lines that start with '#' are comments.
+# For a project mostly in C, the following would be a good set of
+# exclude patterns (uncomment them if you want to use them):
+# *.[oa]
+# *~