append_data() and insert_data() have almost the same implementation.
Change append_data() to simply call insert_data().

Distributions often do builds with no network access available
for both security reasons and also to ensure reproducibility.

This change tells CMake to query the system for a copy of gtest,
but if it's not available, it'll fall back to downloading via
FetchContent.

== DETAILS

- define an interface/abstract class for zlib implementation
- update the code to reference the implementation, remove zlib dependency
- use constructor injection to provide implementations to elfio
- add a test to validate the injected object gets used properly
`

== DETAILS
Honor the compression flag and write compressed section data.

== DETAILS
The Wii U uses a slightly customized ELF format which uses
zlib compression on certain section types.

This commit adds the following:
- add `SHT_` constants for the custom ELF sections
- add `SHF_RPX_DEFLATE` flag used to denote a compressed section
- add code in the section `load()` method to detect the `SHF_RPX_DEFLATE` flag
  and decompress the section

Added some types and strings, table for OS/ABI, added OS/ABI and ABI version to dump

It is a duplication of existing Action CI