config: make yaml parsing self contained lib

[MariusBgm]

Split out SilKitYaml, as selfcontained interface to rapidyaml (including rapidyaml itself).
Allows reusing the YamlReader/Writer in other tools.
this is an internal lib, not part of the public SilKit API surface

[VDanielEdwards]

Looks good to me overall. When using it from the sil-kit repository, the dependency on the rapidyaml target can be added as a subdirectory as well:

cmake_minimum_required(VERSION 3.24)
project(SilKitYamlTest)

add_subdirectory(
  "${CMAKE_CURRENT_SOURCE_DIR}/../sil-kit-b-yaml/ThirdParty/rapidyaml"
  "${CMAKE_CURRENT_BINARY_DIR}/_deps/rapidyaml"
  EXCLUDE_FROM_ALL
)

add_library(rapidyaml ALIAS rapidyaml-static)

add_subdirectory(
  "${CMAKE_CURRENT_SOURCE_DIR}/../sil-kit-b-yaml/SilKitYaml"
  "${CMAKE_CURRENT_BINARY_DIR}/_deps/SilKitYaml"
  EXCLUDE_FROM_ALL
)

add_executable("${PROJECT_NAME}" main.cpp)
target_link_libraries("${PROJECT_NAME}" PRIVATE SilKitYaml)

[MariusBgm]

Looks good to me overall. When using it from the sil-kit repository, the dependency on the rapidyaml target can be added as a subdirectory as well:

cmake_minimum_required(VERSION 3.24)
project(SilKitYamlTest)

add_subdirectory(
  "${CMAKE_CURRENT_SOURCE_DIR}/../sil-kit-b-yaml/ThirdParty/rapidyaml"
  "${CMAKE_CURRENT_BINARY_DIR}/_deps/rapidyaml"
  EXCLUDE_FROM_ALL
)

add_library(rapidyaml ALIAS rapidyaml-static)

add_subdirectory(
  "${CMAKE_CURRENT_SOURCE_DIR}/../sil-kit-b-yaml/SilKitYaml"
  "${CMAKE_CURRENT_BINARY_DIR}/_deps/SilKitYaml"
  EXCLUDE_FROM_ALL
)

add_executable("${PROJECT_NAME}" main.cpp)
target_link_libraries("${PROJECT_NAME}" PRIVATE SilKitYaml)

that's a very good point: consuming the SilKitYaml fails if you do not provide the rapidyaml.
I'd love to have it self contained. e.g. users just have to do a add_subdirectory(sil-kit/SikItYaml) and be done. Maybe move the rapidyaml header into the folder so we can easily consume it, or move SilKitYaml to ThirdParty (since it is just a very thin facade on top of ryml). I'll experiment with this