feat: Config defaults for dune-project

[H-ANSEN]

This is a pull request in reference to and would close #10027 by adding the ability to configure defaults for the authors, maintainers, and license stanzas of the dune-project file. Values are sourced from the config file when using the dune init project command allowing for preferred preset values to be added. Values can be specified by adding the following stanza to the dune config file

(project_defaults
 (authors <string(s)>)
 (maintainers <string(s)>)
 (license <string(s)>))