[clang] [analyzer][NFCI] Move the core.FixedAddressDereference checker to optin.core (PR #181858)

[Ziqing Luo via cfe-commits]

https://github.com/ziqingluo-90 approved this pull request.

Moving this checker out of `core` is a good move to me.  

https://github.com/llvm/llvm-project/pull/181858