[doxygen] Deploy doxygen output to connectedhomeip-doc repo (#7259)
[doxygen] Deploy doxygen output to connectedhomeip-doc repo (#7259)

Currently, doxygen HTML files are deployed to "gh-pages"
branch of the main connectedhomeip repo. As a result, it
takes more and more time to checkout the entire repo.

Move the doxygen output to an external repository.
nestlabs/connectedhomeip,project-chip/connectedhomeip,project-chip/connectedhomeip,project-chip/connectedhomeip,project-chip/connectedhomeip,nestlabs/connectedhomeip,project-chip/connectedhomeip,nestlabs/connectedhomeip,nestlabs/connectedhomeip,project-chip/connectedhomeip,nestlabs/connectedhomeip,nestlabs/connectedhomeip,nestlabs/connectedhomeip