Support building an allow-list of providers (#527)

* Add providers subcommand to verify providers

Allows users to check what providers are available

* Fix version output to add new line

This command was totally broken until we moved around the call to
`initConfig()`, this just fixes the output now that it works.

* Flip boolean of provider include tags

All providers are still included by default and fix tags using the old
format.

cmd/version.go

@@ -27,7 +27,7 @@ var versionCmd = &cobra.Command{
 	Short: "Show the version of the program",
 	Long:  `Show the version of the program`,
 	Run: func(cmd *cobra.Command, args []string) {
-		fmt.Printf("Version: %s, Built: %s", version.Version, version.BuildTime)
+		fmt.Printf("Version: %s, Built: %s\n", version.Version, version.BuildTime)
 	},
 }