Add more shim reviewers

[AlexeyPetrenkoOracle]

Hi.

I think it's clear for everyone that this process is barely working now. I have a request which is open for six and a half months, and there is still no ETA to resolve it.
As a result, Oracle Linux carries shim with known bugs for months, which is quite disturbing since shim is a security component, and we need a way to release the updates promptly.

I believe we need more reviewers and setup review rules to streamline this process. I can volunteer myself. @jsegitz from SUSE might be also interested.

Thanks.

Alexey

[AlexeyPetrenkoOracle]

This one is apparently a duplicate of this one: #84