Allow boards to display issues from filters where the issuekeys are in lowercase

Current functionality has it such that if the issue keys in a filter are all in lowercase, the filter itself will work and return the issues. When using the filter in a board, it will return no results.

This request is to allow boards to be able to use filters where the issue keys are lowercase and return the same results as when using the filter independently.

Steps to Reproduce

1. Create a board filter to include all issue keys in lowercase, from all the required projects.
   Example:

    issuekey in (aa-1, aa-2, bb-1, bb-2, cc-1, cc-2) ORDER by RANK 

1. Verify the Projects in Board section in board settings and see that no projects are displayed.

Expected Results

Projects under Projects in Board section should be displayed irrespective of the case of the issuekeys in the board filter.

Actual Results

Projects are displayed only if the issue keys are mentioned in uppercase.

Workaround

Edit the board filter such that at least 1 issue key for each project is mentioned in uppercase.
Example:

 issuekey in (AA-1, aa-2, BB-1, bb-2, CC-1, cc-2) ORDER by RANK