Partially addresses #47424.

Revert "Merge branch 'rd-43185-revert-sanitize-extra-blank-spaces-used-when-uploading-a-ssh-key' into 'master'"

This reverts commit e607fd79.

This reverts commit a58f8c32, reversing
changes made to cd5d75c3.

By caching the number of personal SSH keys we reduce the number of
queries necessary on pages such as ProjectsController#show (which can
end up querying this data multiple times).

The cache is refreshed/flushed whenever an SSH key is added, removed, or
when a user is removed.

This makes things simpler as no scheduling is involved. Further we
remove the need for running a SELECT + UPDATE just to get the key and
update it, whereas we only need an UPDATE when setting last_used_at
directly in a request.

The added service class takes care of updating Key#last_used_at without
using Sidekiq. Further it makes sure we only try to obtain a Redis lease
if we're confident that we actually need to do so, instead of always
obtaining it. We also make sure to _only_ update last_used_at instead of
also updating updated_at.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/36663

`allowed_key_types` is removed and the `minimum_<type>_bits` fields are
renamed to `<tech>_key_restriction`. A special sentinel value (`-1`) signifies
that the key type is disabled.

This also feeds through to the UI - checkboxes per key type are out, inline
selection of "forbidden" and "allowed" (i.e., no restrictions) are in.

As with the previous model, unknown key types are disallowed, even if the
underlying ssh daemon happens to support them. The defaults have also been
changed from the lowest known bit size to "no restriction". So if someone
does happen to have a 768-bit RSA key, it will continue to work on upgrade, at
least until the administrator restricts them.

This is an amalgamation of:

* Cory Hinshaw: Initial implementation !5552
* Rémy Coutable: Updates !9350
* Nick Thomas: Resolve conflicts and add ED25519 support !13712

Use the EnforcedStyleForMultiline: no_comma option.

Signed-off-by: Rémy Coutable <remy@rymai.me>

Use Gitlab::ExclusiveLease to make sure that we enqueue Sidekiq job
at most once per day for given key.

Addresses: Issue #13810

1. Adds a last_used_at attribute to the Key table/model
2. Update a key's last_used_at whenever it gets used
3. Display how long ago an ssh key was last used

Signed-off-by: Rémy Coutable <remy@rymai.me>

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7383#note_18517263

ref: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6763

This reverts commit 3e991230.

# Conflicts:
#	app/models/project.rb

In 8278b763 the default behaviour of annotation
has changes, which was causing a lot of noise in diffs. We decided in #17382
that it is better to get rid of the whole annotate gem, and instead let people
look at schema.rb for the columns in a table.

Fixes: #17382

Related to #2235.

This is done by:
1. Delaying the notification sending after the SSH key is commited in DB
2. Gracefully exit the mailer method if the record cannot be found

signe-in -> signed-in
go_to_gihub_for_permissions -> go_to_github_for_permissions
descendand -> descendant
behavour -> behaviour
recepient_email -> recipient_email
generate_fingerpint -> generate_fingerprint
dependes -> depends
Cant't -> Can't
wisit -> visit
notifcation -> notification
sufficent_scope -> sufficient_scope?
levet -> level

[\d\h] is the same as \h

Add system hook for ssh key create and destroy
Update and fix documentation
Update tests