Many parameters under Server are missing components

[jhiemstrawisc]

I noticed this while writing the issue for #1802 -- many of the Server.XYZ config params are missing at least one server component. For example:

name: Server.ExternalWebUrl
description: |+
  A URL indicating the Pelican web interface and internal web APIs address as it appears externally.

  Port number will be stripped if it's 443, from `Server.WebPort` or directly set through `Server.ExternalWebUrl`.
type: url
default: https://${Server.Hostname}:${Server.WebPort} (for ${Server.WebPort} != 443)
components: ["origin", "director", "registry"]

Caches also have a WebUI affected by this, but the cache as not listed as a component.

If there are Server.XYZ config params that really don't apply to one of our server components, we might need to think about this naming convention.

[jhiemstrawisc]

Another note -- we should mark Server.Modules as hidden because the CLI tool it mentions (pelican serve) is also hidden. It also doesn't affect all components, so that should be corrected for our internal docs.