Expose net_ipv4_create, net_ipv6_create, and net_udp_create in standard header

[galak]

Currently some of the modem drivers (drivers/modem/hl7800.c and drivers/modem/wncm14a2a.c) are calling net_ipv6_create, net_ipv4_create and net_udp_create which requires having:

zephyr_library_include_directories(${ZEPHYR_BASE}/subsys/net/ip) in CMakeLists.txt. If these are suppose to be APIs that can be called on the networking subystem we should look to move them into include/net/ somewhere.

[galak]

@jukkar was looking at various places we do zephyr_library_include_directories and if there is some implied cleanup that needs to happen. This is one area related to networking interfaces and modem. Don't really know much about it beyond that.

[jukkar]

I would like not to expose these APIs by putting them to include/net, as they are meant for internal use. Is there some issue if zephyr_library_include_directories is used in the driver?
Calling these private APIs from drivers is ok, but I would like to avoid exposing them to applications.

[galak]

I would like not to expose these APIs by putting them to include/net, as they are meant for internal use. Is there some issue if zephyr_library_include_directories is used in the driver?
Calling these private APIs from drivers is ok, but I would like to avoid exposing them to applications.

There's not a specific issue, just trying to ensure some level of encapsulation - even if its between a subsystem a driver.

[galak]

@jukkar will close this out, we need a general solution/agreement on how subsystems export APIs to other parts of zephyr (not application).