In the past this class would use Project#get_issue to retrieve an issue
by its ID. This method would automatically determine whether to return
an Issue or ExternalIssue.

This commit changes IssueReferenceFilter to handle external issues again
and in a somewhat more explicit manner than before.

Fixes gitlab-org/gitlab-ce#18827

Fix RangeError exceptions when referring to issues or merge requests outside of max database values

When using #XYZ in Markdown text, if XYZ exceeds the maximum value of a signed 32-bit integer, we get an exception when the Markdown render attempts to run `where(iids: XYZ)`. Introduce a method that will throw out out-of-bounds values.
    
Closes #18777

See merge request !4777

When using #XYZ in Markdown text, if XYZ exceeds the maximum value of a signed 32-bit integer, we
get an exception when the Markdown render attempts to run `where(iids: XYZ)`. Introduce a method
that will throw out out-of-bounds values.

Closes #18777

Fixes item icon state when for issues that have the same labels assigned

## What does this MR do?
Previously if all issues had the same labels the dropdown was showing the labels with indeterminate stated which is wrong. This MR fixes that and shows the correct state.

## What are the relevant issue numbers?
Fixes #18714

## Screenshots (if relevant)

**Before**

![label-before](/uploads/c65aa051e773dfea898a0d19767d6ade/label-before.gif)

**After**

![label](/uploads/73fd657d104d1081e189e0a9547d483b/label.gif)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- [ ] Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4721

1. An exception would be raised if the filter was called with an invalid
   URI. Mainly because we weren't catching the `Addressable` exception.

2. This commit fixes it and adds a spec for the filter.

Implement custom notification level options

![Screen_Shot_2016-06-17_at_15.31.43](/uploads/3fc47d2f461b3e8b67bb8acaa304cf99/Screen_Shot_2016-06-17_at_15.31.43.png)

![Screenshot_from_2016-06-15_10-52-27](/uploads/88dbdd21d97e80ee772fe08fa0c9b393/Screenshot_from_2016-06-15_10-52-27.png)

part of #12758 

See merge request !4389

Ensure that group owner cannot request access to a project of their group

## What does this MR do?

It fixes two things:

- 91ad995d69e1a0f8991fd896f1d9febc109273fe Ensure that group owner cannot request access to a project of their group
- ec3ff061148d556757e7cd486cdc6083d77acf34 Ensure group/project owners can see their members' access_level (see the commit message for details)

## Are there points in the code the reviewer needs to double check?

Not really, these are pretty simple fixes.

## Why was this MR needed?

Because there was an issue created!

## What are the relevant issue numbers?

Fixes #18717.

## Does this MR meet the acceptance criteria?

- [x] CHANGELOG is not needed since the bug is only present in a 8.9 RC
- [x] Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4729

# Conflicts:
#	app/controllers/projects/todos_controller.rb

API endpoints for award emoji

Closes #10884 

See merge request !4575