Add a starting date to milestones

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/23704

See merge request !7484

There may be more tables but these were the tables that were problematic
for GitLab.com due to foreign key constraints (without cascading
deletes).

Allow to block JIRA events for commits and merge requests

implements #5541 

See merge request !7469

Resolve "Display "folders" for environments"

## What does this MR do?
Adds the ability to show the grouped environments inside "folders".
Adds several reusable vue components in order to accomplish the recursive tree data structure presented.

For the individual components, Jasmine tests were added.
For the ones that depend of an API response, rspec tests are used.


## Screenshots (if relevant)
![Screen_Shot_2016-11-16_at_02.00.13](/uploads/1278012c8639b999b53f080728d283e1/Screen_Shot_2016-11-16_at_02.00.13.png)
![Screen_Shot_2016-11-16_at_02.00.25](/uploads/a3d65416ddb553e1b8f0f4c8897a75dc/Screen_Shot_2016-11-16_at_02.00.25.png)
![Screen_Shot_2016-10-17_at_16.08.50](/uploads/af63efe1d2cbd5fc069408622ef4b607/Screen_Shot_2016-10-17_at_16.08.50.png)


![environments](/uploads/b5a1801766d82ab176fc60f96b6968cb/environments.gif)
## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG.md) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [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 it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?
Closes #22539

See merge request !7015

Precalculate authorized projects in database

## What does this MR do?
It caches user's authorized projects in database instead of using multiple unions, which should simplify and speed-up things since this operation (getting authorized projects) is used a lot.

## Are there points in the code the reviewer needs to double check?
Did we miss a scenario where we need to refresh the list of projects?

## Does this MR meet the acceptance criteria?

- [x] [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
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [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 it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?
#23150 

See merge request !6839

Closes #23150