Group token HTTP authentication

What does this MR do?

Group access tokens should be able to pull/push with git over http: #330718 (closed)

When attempting to use a resource access token to authenticate against git over http, add a check to see if the resource access token belongs to a user in either the project or an ancestor group; if yes, allow authentication.

This MR is an extension of !40635 (merged), which introduced the ability for project access tokens to authenticate over http.

To generate a group access token:

pry(main)> root = User.find(1) # group admin
pry(main)> group = Group.find(109) # the group you want to create a token for
pry(main)> bot = Users::CreateService.new(root, { name: 'group_token', email: 'group_109_bot@example.com', username: 'group_109_bot', user_type: :project_bot }).execute # create the bot user
pry(main)> bot.confirm
pry(main)> group.add_user(bot, :maintainer) # add it to the group
pry(main)> token = bot.personal_access_tokens.create(scopes:[:api, :write_repository], name: 'group_token') # give it a personal access token
pry(main)> gtoken = token.token # get the token value; note that we need the token value and not token_digest

% GROUPTOKEN = <gtoken value from above>

Before:

% git clone http://group_107_bot2:$GROUPTOKEN@127.0.0.1:3000/newgroup/newproject.git
Cloning into 'newproject'...
remote: HTTP Basic: Access denied
fatal: Authentication failed for 'http://127.0.0.1:3000/newgroup/newproject.git/'

After:

% git clone http://group_107_bot2:$GROUPTOKEN@127.0.0.1:3000/newgroup/newproject.git
Cloning into 'newproject'...
remote: Enumerating objects: 3, done.
remote: Counting objects: 100% (3/3), done.
remote: Total 3 (delta 0), reused 0 (delta 0), pack-reused 0
Receiving objects: 100% (3/3), done.
warning: remote HEAD refers to nonexistent ref, unable to checkout.

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Does this MR meet the acceptance criteria?

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• I have self-reviewed this MR per code review guidelines.
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• This change is backwards compatible across updates, or this does not apply.

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• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
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Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team