devel/mongo-c-driver: Rework port

• Use upstream release archive as recommended by Porters Handbook
• Remove cyrus-sasl2 from LIB_DEPENDS
• Use framework helpers when possible
• Rearrange Makefile to better follow Porters Handbook and easier readability
• Don't install unnecessary files in share directory

PR: 269625
Reviewed by: Krzysztof <ports@bsdserwis.com> (maintainer)