Feature/58159 fixed set of project stages and gates editable on project overview page

[dombesz]

Ticket

https://community.openproject.org/wp/59287

What are you trying to accomplish?

Add the foundation structure for the Stages and Gates epic. It consists of:

• Adding a feature flag
• Adding the stages and gates set up as instance wide models
• Setting up Project related stages and gates models
• Seeding a predefined set of stages and gates as outlined in PM2 specification
• Translating the predefined seeds (Happens on Crowdin)
• Handle data migration for existing instances
• Add newly specced Gate seeds

What approach did you choose and why?

The approach chosen is to have a base model called LifeCycle to share behaviour between the Stage and Gate models. Stage and Gate models are mostly the same, except the type.

Additionally a second set of project specific Project::LifeCycle models are defined alongside with Project::Stage and Project::Gate. These models hold project specific information about each LifeCycle, such as the start and end dates of life cycles defined inside each project. The Project::Stage required a start_date and end_date fields, while the Project::Gate requires a date field. These are all mapped in the Project::LifeCycle model with STI.

Merge checklist

• Added/updated tests
• Added/updated documentation in Lookbook (patterns, previews, etc)
• Tested major browsers (Chrome, Firefox, Edge, ...)