Move the legal documentation generator to the PMI

The legal documentation generator is currently hosted on the /projects page. Moving it to the PMI feels like a better fit.

The legal documentation generator uses project metadata -- entirely from the PMI -- to generate various (mostly) legal documents that we ask projects to put into their repositories, including the CONTRIBUTING, LICENSE, NOTICE, and SECURITY files, along with a copyright and licence header for source files. All of the generated content is considered to a starting point (or template) for project teams to use and modify. In a lot of cases, the generated content is complete and requires no modification.

The page also includes a table that has a row for each repository associated with the project, along with an indication of whether or not the various documents appear in that repository. For this, data from the dashboard database is used.

The document templates are rendered in Markdown format. I had attempted to make it support multiple formats; as a result, the implementation is more abstract than it needs to be.

I'll capture requirements for specific elements of the page in threads on this issue.