Bulk insert members and member_roles for sub projects

[sanak]

Performance up patch for many sub projects and members.
TODO:

• Check N+1 query by bullet gem
• CI with using https://github.com/hidakatsuya/action-setup-redmine
• MySQL
• SQLite

[sanak]

bullet gem reports the following log when changing parent project, so consider to follow advice.

user: sanak
PATCH /projects/sub-project-1-2
USE eager loading detected
  Member => [:member_roles]
  Add to your query: .includes([:member_roles])
Call stack
  /Users/sanak/Build/rb/redmine/app/models/project.rb:1074:in `block (2 levels) in add_inherited_member_roles'
  /Users/sanak/Build/rb/redmine/app/models/project.rb:1071:in `block in add_inherited_member_roles'
  /Users/sanak/Build/rb/redmine/app/models/project.rb:1057:in `add_inherited_member_roles'
  /Users/sanak/Build/rb/redmine/app/controllers/projects_controller.rb:216:in `update'
  /Users/sanak/Build/rb/redmine/lib/redmine/sudo_mode.rb:78:in `sudo_mode'

Also, consider to cache (or merge) bulk insert result returning ids not to execute find_by query again.

        parent.memberships.each do |parent_member|
          member = Member.find_or_initialize_by(:project_id => self.id, :user_id => parent_member.user_id)
          :
        parent.memberships.each do |parent_member|
          # Member should exist
          member = Member.find_by(:project_id => self.id, :user_id => parent_member.user_id)
          parent_member.member_roles.each do |parent_member_role|
          :