Merge two milestones implementations:`checkpoint-review` and `final-designs` into one

[maxceem]

From here #2361 (comment)

we also need to remove the additional new milestones created for both checkpoint and final-designs which we created to support the data pushed from add-links , as its hard to maintain almost similar component. we can use logic in actual checkpoint-review and final designs milestones to render data for both old and new timelines, so that maintenance is easy for the components.

Agree on this, already few changes had to dpulicate into two components.

Aha! Link: https://topcoder.aha.io/features/TCCONNECT-393

[vikasrohit]

@maxceem Its not about merging checkpoint-review and final-designs into one, I they have different purposes and behaviour. Though, we can use same component for them as well by using hoc(s) for rendering the design selection portion in the milestone. I think while this would also be a good refactoring, however, the point we raised in #2361 (comment) is to use single component for read only and non read only modes e.g. merging MilestoneTypeFinalDesignsSelectionOnly and MilestoneTypeFinalDesigns into one i.e. using MilestoneTypeFinalDesigns even for SelectionOnly mode. Similarly for MilestoneTypeCheckpointReviewOnly and MilestoneTypeCheckpointReview.

[vikasrohit]

@maxceem Apologies, I think I misread your description. Saw the changes after posting the comment 😬, seems like you have done exactly what I described above. Thanks.

[maxceem]

@vikasrohit yeah, I just was not clear in this issue description...

[maxceem]

@RishiRajSahu this is already in dev branch and can be closed.

[RishiRajSahu]

@maxceem thanks for bringing it to attention.