Split `read_push_rules` permission from `admin_push_rules`
## Description In the Web IDE we are reading from `projects/:id/push_rules` ([see relevant code](https://gitlab.com/gitlab-org/gitlab-web-ide/-/blob/ad44e2ff5cc8bdcd043a2bcadd13920013078496/packages/vscode-mediator-commands/src/commands/fetchProject.ts#L16)) to give instant feedback on commit messages while the user is writing a commit. This endpoint is currently guarded by a [check for `:admin_push_rules` ability](https://gitlab.com/gitlab-org/gitlab/-/blob/a0acd6723de19f92f4aff545e8043f56e39caab4/ee/lib/api/project_push_rule.rb#L7). Is this private information? Can we open up this endpoint to anyone that can read the project? ## Acceptance Criteria - [ ] If we can loosen the restriction on this endpoint, let's create a new ability for `:read_push_rules` to manage this permission. - [ ] Update [`project_push_rule.rb`](https://gitlab.com/gitlab-org/gitlab/-/blob/a0acd6723de19f92f4aff545e8043f56e39caab4/ee/lib/api/project_push_rule.rb) to authroize for `:read_push_rules` on the `get` request.
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