Mirror source tree for adapter headers

[hgangwar]

Install adapter headers via DIRECTORY install.

Changes

• Defined ADAPTER_HEADERS.
• Installed headers from ADAPTER_HEADERS into their respective directories.
• Included create_field.h in examples for external-usage-example usage testing.

[hgangwar]

@jacobmerson

[jacobmerson]

We had a breif discussion offline. We are going to investigate converting our header definitions over to FILE_SETS which should maintain the structure.

https://cmake.org/cmake/help/latest/command/install.html#id5

This approach looks like it may also enable us to set up targets that check that the header files can be correctly included, which would be a nice test to include to our CI/CD testing.

https://cmake.org/cmake/help/latest/prop_tgt/VERIFY_INTERFACE_HEADER_SETS.html#prop_tgt:VERIFY_INTERFACE_HEADER_SETS

[jacobmerson]

@hgangwar this looks good. Are there other header lists that should be converted to use this method? If so, lets implement that and then make this PR not a draft.

[hgangwar]

Added field_layout_communicator.h to PCMS_HEADERS, required by field_communicator2.h.

[jacobmerson]

I will merge when remaining headers are added to respective FILE_SET so we have a consistent handling of headers in our CMake.