app-tools, tools: move distributed binaries to the appropriate folder

This is an apparently non-controversial change. These files, like gimp-debug-tool, are distributed for linux, windows or macos. So, they should be in the app-tools folder, according to devel-docs.

However, the original intention of the 5893d2dc message is different than what is actually written in the devel-docs (which reproduced in this MR commit message). So, I will leave to @Jehan the final word.