Convert domain to lowercase in pihole -q

[yubiuser]

What does this PR aim to accomplish?:

Converts the domain passed to pihole -q to lowercase before running the actual search.

Fixes #5199

How does this PR accomplish the above?:

tr '[:upper:]' '[:lower:]'

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Resolved

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/pi-hole-ftl-v5-22-web-v5-19-and-core-v5-16-1-released/61999/1