Copy code/data from fleeting into installer

Using git-filter-repo, rewrite the commits in fleeting to place files in their correct locations in the installer. The resulting commits can then be merged into the agent branch of the installer with a pull request.

Data files should be moved to e.g. data/data/agent, appending the suffix .template to any that are templated.

Code files that are needed by the installer should be moved to appropriate directories that have the agent team in the OWNERS.

Keep the git-filter-repo script so that development can continue in parallel on fleeting until we are ready to switch CI over to the installer implementation.