Make lfric eg20 compile

[arporter]

Currently eg20 just generates an algorithm subroutine however @hiker says:

"I could get this to compile with our infrastructure files by adding function_space_collection_mod.F90 to our infrastructure (with a small change to get around code differences between our version and the current lfric infrastructure) and a dummy main program It certainly won't run, but just being able to compile this would be great."

so it would be good to do this.