GITC-580: allows for multiple clr_rounds to be selected at once

[gdixon]

Description

This PR addresses @frankchen07 feedback in this comment: #9725 (comment) - and ensures the following behaviour:

GIVEN I am looking to filter by a primary matching category
WHEN I click on my primary-level selection
THEN the primary item is highlighted
AND the page returns all grants eligible in rounds under the primary matching category selection
AND the pillbox reads "Grant Round: [primary]".

Refers/Fixes

Fixes: GITC-580

Testing

Tested locally

[nutrina]

LGTM