Add ADBC to official extensions

[adsharma]

Summary

• add ADBC to the runtime official extension allowlist
• add a regression check for case-insensitive official extension lookup

Testing

$ pixi add libadbc-driver-manager
$ install_name_tool -rpath \
    /Users/runner/work/ladybug/ladybug/.pixi/envs/default/lib \
    /path/to/.pixi/envs/default/lib 
    
lbug> load adbc;
┌──────────────────────────────────┐
│ result                           │
│ STRING                           │
├──────────────────────────────────┤
│ Extension: adbc has been loaded. │
└──────────────────────────────────┘
(1 tuple)
(1 column)