Refactor adding EosioChain INTERFACE library for use in add_eosio_test_executable macro and by itself.

[oschwaldp-oci]

This refactor creates an INTERFACE library called EosioChain which can be used externally to leap as a library for target_link_libraries. In an repository that wants to depend on and link against EosioChain, it can now be done by simply:

find_package(eosio)
target_link_libraries( <myNewTarget> PRIVATE EosioChain ...)

[spoonincode]

How difficult would it be to refactor this cmake file to present maybe a add_library(libtester STATIC IMPORTED). Then the existing add_eosio_test_executable would just link to the IMPORTED libtester, but when you're not making a test executable you would just target_link_libraries(whatever libtester)

Adding dependencies like this makes it difficult to know the union of all downstream dependencies when reviewing this file in the future.

[oschwaldp-oci]

How difficult would it be to refactor this cmake file to present maybe a add_library(libtester STATIC IMPORTED). Then the existing add_eosio_test_executable would just link to the IMPORTED libtester, but when you're not making a test executable you would just target_link_libraries(whatever libtester)

Adding dependencies like this makes it difficult to know the union of all downstream dependencies when reviewing this file in the future.

@spoonincode -- How about going the direction of an INTERFACE library like you had also mentioned out of band earlier? Proposal: 3e22bd1

[spoonincode]

Yes true, INTERFACE is considerably easier than IMPORTED in this case since we have a handful of static libraries.