Add .hpp header and deprecate .h

[sloretz]

This PR is two commits and should be rebase and merged to capture the moved file in history. The first commit renames retriever.h to retriever.hpp with no other changes. The second commit creates a new retriever.h that warns it is deprecated and includes retriever.hpp as well as making the code changes to use retriever.hpp.

[sloretz]

CI linux build: --packages-above resource_retriever test: --packages-select resource_retriever to look for warnings downstream:

[clalancette]

One minor question, and it looks like CI failed. Once those are fixed this is fine with me, thanks for doing this.

[sloretz]

One minor question, and it looks like CI failed.

Oops, I used the wrong build args. New build --packages-above-and-dependencies resource_retriever test --packages-select resource_retriever

• Linux
• Windows

[sloretz]

CI (build: --packages-above-and-dependencies resource_retriever test: --packages-select resource_retriever rviz_common rviz_default_plugins rviz_rendering rviz_rendering_tests)

• Linux
  • java traceback, rebuilding:
• Linux-aarch64
  • java traceback, rebuilding:
    • java traceback, rebuilding:
• macOS
• Windows