lib/param move source4 param code to the top level

lib/param move source4 param code to the top level

This is done so that the lpcfg_ functions are available across the whole
build, either with the struct loadparm_context loaded from an smb.conf directly
or as a wrapper around the source3 param code.

This is not the final, merged loadparm, but simply one step to make
it easier to solve other problems while we make our slow progress
on this difficult problem.

Andrew Bartlett