Handle nil commits in Gitlab::PushDataBuilder.build

Closes #13469

See merge request !2825

Add new data to project in push, issue, merge-request and note webhooks data

_Originally opened at !2738 by @bugagazavr._

- - -

**What does this MR do?**

Adds more data to hooks, makes repository data in all hook more dry ( use one hook_attrs method for repository data in all hooks )

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

1. https://gitlab.com/bugagazavr/gitlab-ce/blob/extend-hooks/app/models/project.rb#L738
2. https://gitlab.com/bugagazavr/gitlab-ce/blob/extend-hooks/app/models/concerns/issuable.rb#L132
3. https://gitlab.com/bugagazavr/gitlab-ce/blob/extend-hooks/lib/gitlab/push_data_builder.rb#L52
4. https://gitlab.com/bugagazavr/gitlab-ce/blob/extend-hooks/lib/gitlab/note_data_builder.rb#L56

**Why was this MR needed?**

More information about user for push events, and more data about repositiry ( project )

**What are the relevant issue numbers?**

No

**Screenshots (if relevant)**

No

See merge request !2788

Closes #13469

- Apply the RelativeLinkFilter filter to other formats, e.g.,
  reStructuredText so links from the Files view or the Project view work
- Remove the AsciidocPipeline pipeline

Fixes #3533.

- Add `avatar_url`, `description`, `git_ssh_url`, `git_http_url`,
  `path_with_namespace` and `default_branch` in `project` in push, issue,
  merge-request and note webhooks data
- Deprecate the `ssh_url` in favor of `git_ssh_url` and `http_url` in
  favor of `git_http_url` in `project` for push, issue, merge-request and
  note webhooks data
- Deprecate the `repository` key in push, issue, merge-request and
  note webhooks data, use `project` instead

This allows for future pipelines to more easily define a custom
whitelist.

Closes #12900

Currently any spam detected by Akismet by non-members via API will be logged
in a separate table in the admin page.

Closes #5612