Agreement start and end dates should be the earliest period start and latest period end date respectively

Purpose:
The Agreement start and end dates are more constant and easily understandable by users and not dependent on whether there is a current period for the agreement

Description:
Agreement start and end dates should be calculated based on the earliest start date and latest end dates across all periods for the agreement.

If there is a period with an unset end date, the agreement end date should also be unset

If a period is edited, added or deleted, the agreement start/end dates should be updated

In the Agreements search and filter MCL the Agreement start and end dates should be displayed (in place of the current "Period start" and "Period end" date columns currently displayed)

In the Agreements view pane, at the top of the agreement the Agreement start and end dates should be displayed (in place of the current "Period start" and "Period end" date columns currently displayed)

User story statement(s):

As a e-resource librarian
I want to be able to view the start date for an agreement, meaning the date on which the agreement first started (rather than in relation to the current period)
so that I can easily understand when an agreement first starts/started

As a e-resource librarian
I want to be able to search the start date for an agreement, meaning the date on which the agreement first started (rather than in relation to the current period)
so that I can easily find agreements that starts/started on a particularly date

As a e-resource librarian
I want to be able to view the end date for an agreement, meaning the date on which the agreement ends altogether (rather than in relation to the current period)
so that I can easily understand when an agreement ends/ended

As a e-resource librarian
I want to be able to search the end date for an agreement, meaning the date on which the agreement ends altogether (rather than in relation to the current period)
so that I can easily find agreements that end/ended on a particularly date

Scenarios:

1. Scenario:
   • Given an agreement
   • When I view the agreement start date
   • Then it should be the earliest start date across all agreement period start dates

• • Given an agreement in which all periods have end dates
  • When I view the agreement end date
  • Then it should be the latest end date across all agreement period end dates

• • Given an agreement in which one of the agreement periods has an unset end date
  • When I view the agreement end date
  • Then it should be unset

• • Given an agreement
  • When the agreement appears in the Agreement search and filter MCL
  • Then the agreement start and end dates (if set) should display in the MCL as columns (in place of the current "Period start" and "Period end" dates

• • Given an agreement
  • When the agreement appears in the Agreement view pane
  • Then the agreement start and end dates (if set) should display at the top of the Agreements view pane (in place of the current "Period start" and "Period end" dates