These are datasets for Ghidra's Function Identification analyzer.
To add them to an installation, copy them to Ghidra/Features/FunctionID/data.
These are in their 'packed' form.
Ghidra should unpack them on first use.
To add them to a source tree, copy them into ghidra.bin/Ghidra/Features/FunctionID/src/main/fidb.
Note that ghidra.bin is a sibling directory of your clone of ghidra.
The Gradle task prepDev will unpack these into a directory for Ghidra (as run from Eclipse) to use.
The Gradle task buildGhidra will unpack these and include them in the build output.