* Some more e-mail notification fixes

A few more small e-mail notification fixes/changes

* Style footer of notification email to be smaller
* Include text for when pull request is merged
* Don't include original body of issue or PR when merging/closing by
setting issue.Content to "" in these cases

* Set Re: prefix and meessage-ID headers based on actName instead of checking for a
comment. This fixes a bug where certain actions that didn't have a
comment were setting Message-ID instead of In-Reply-To which caused some
mail programs not to show those messages as they would have had the same
Message-ID as a previous message. Also fixes the case where a final
comment and closing message would have been displayed out of order if
you didn't have a copy of the original issue/pr cretion message.

* Update other template footers for consistency

* Add ActionCommentPull action

Adds ActionCommentPull action to distinguish between a comment on an
issue and on a pull request

* Update modules/notification/action/action.go

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

* Mail issue subscribers, rework the function

* Simplify a little more

* Fix unused variable

* Refactor mail delivery to avoid heavy load on server

* Avoid splitting into too many goroutines

* Fix comments and optimize GetMaileableUsersByIDs()

* Fix return on errors

* Add template capability for issue mail subject

* Remove test string

* Fix trim subject length

* Add comment to template and run make fmt

* Add information for the template

* Rename defaultMailSubject() to fallbackMailSubject()

* General rewrite of the mail template code

* Fix .Doer name

* Use text/template for subject instead of html

* Fix subject Re: prefix

* Fix mail tests

* Fix static templates

* [skip ci] Updated translations via Crowdin

* Expose db.SetMaxOpenConns and allow non MySQL dbs to set conn pool params (#8528)

* Expose db.SetMaxOpenConns and allow other dbs to set their connection params
* Add note about port exhaustion

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Prevent .code-view from overriding font on icon fonts (#8614)

* Correct some outdated statements in the contributing guidelines (#8612)

* More information for drone-cli in CONTRIBUTING.md

* Increases the version of drone-cli to 1.2.0
* Adds a note for the Docker Toolbox on Windows

Signed-off-by: LukBukkit <luk.bukkit@gmail.com>

* Fix the url for the blog repository (now on gitea.com)

Signed-off-by: LukBukkit <luk.bukkit@gmail.com>

* Remove TrN due to lack of lang context

* Redo templates to match previous code

* Fix extra character in template

* Unify PR & Issue tempaltes, fix format

* Remove default subject

* Add template tests

* Fix template

* Remove replaced function

* Provide User as models.User for better consistency

* Add docs

* Fix doc inaccuracies, improve examples

* Change mail footer to math AppName

* Add test for mail subject/body template separation

* Add support for code review comments

* Update docs/content/doc/advanced/mail-templates-us.md

Co-Authored-By: 6543 <24977596+6543@users.noreply.github.com>

* Send email to assigned user

* Only send mail if enabled

* Mail also when assigned through API

* Need to refactor functions from models to issue service

* Refer to issue index rather than ID

* Disable email notifications completly at initalization if global disable

* Check of user enbled mail shall be in mail notification function only

* Initialize notifications from routers init function.

* Use the assigned comment when sending assigned mail

* Refactor so that assignees always added as separate step when new issue/pr.

* Check error from AddAssignees

* Check if user can be assiged to issue or pull request

* Missing return

* Refactor of CanBeAssigned check.

CanBeAssigned shall have same check as UI.

* Clarify function names (toggle rather than update/change), and clean up.

* Fix review comments.

* Flash error if assignees was not added when creating issue/pr

* Generate error if assignee users doesn't exist

* move all mail related codes from models to modules/mailer

* fix lint

* use DBContext instead Engine

* use WithContext not WithEngine

* Use DBContext instead of Engine

* don't use defer when sess.Close()

* move DBContext to context.go and add some methods

* move mailer from modules/ to services

* fix lint

* fix tests

* fix fmt

* add gitea copyright

* fix tests

* don't expose db functions

* make code clear

* add DefaultDBContext

* fix build

* fix bug