How to create a view to display all the files in an extension?
Take a look at the documentation for civix. To create a page like the mailing templates you could use civix generate:form, as described at https://docs.civicrm.org/dev/en/latest/extensions/civix/#generate-form
If you prefer to create an angular page, you can also use civix to generate the basic code: https://docs.civicrm.org/dev/en/latest/framework/angular/quickstart/#create-an-angular-module