Improved contribution searching

We just made a number of improvements to the contribution search page to help treasurers more easily find specific contributions:

1. You can now select multiple contributors when searching. Previously, you could only select a single person, couple, or donor. Now, you can choose any combination of people or donors, and the results will include contributions made by any of them.
2. A new "Exact match" option lets you limit results to contributions made directly by the selected contributors — excluding any that were simply credited to them. This is especially helpful when reviewing contributions based on who will actually be receiving the tax receipt.
3. A new "Receipt number" filter makes it easy to find all contributions associated with a specific receipt.

In addition to these search improvements, we also added a new "View contributions" option for each receipt on the "Receipts" and "Create Receipts" pages. This allows you to quickly search for all the contributions that make up a receipt — really helpful if you need to make changes to those contributions.

And finally, we fixed an issue where the contribution search page didn’t support pagination — previously, only the first 15 results were shown. You can now page through all matching contributions as expected.