Bulk copy in and to proposals

Description:
The idea is to allow users to copy all or selected parts of data from another proposal or within the same proposal. In many cases, copying the entire proposal and then removing unnecessary parts might be sufficient. However, there may be use cases where users need to combine large sets of data from multiple proposals or duplicate sections of a proposal within the same proposal.

Use Case / Example:
If a user previously split a large proposal into several smaller ones due to performance issues—which have now been resolved—they may want to merge the data back into a single proposal.