feat: remaining effort

[derrabauke]

Progress tool tip

• show remaining effort for task
• show remaing effort for project (calculated in backend)

Activities/timesheet (main page)

• add new input field for remaining effort (only for active remaining efforts)
• replace “Not billable” and “Needs review” with icons
  

Projects page

• add checkbox/toggle switch to de/activate remaining effort on project
• after activation, add field on tasks to set remaining effort

Statistics

• add a new column: remaining effort / estimated total effort

• update graphs according to screenshot
  

• red line: estimated time

• green box: remaining effort < estimated time

• red box: remaining effort > estimated time

• update test

[derrabauke]

Buglist

• Don't show the red line for statistics where no remaining effort is set.