rclone: add option to set log-level (#8105)

Add an option to set rclone's log-level per mount:
programs.rclone.remotes.<name>.mounts.<name>.logLevel = "DEBUG";
If no value is set, it'll use rclone's implicit default ("NOTICE")

Previously, the debug log-level got enforced (via "-vv"),
which caused noisy logs, and there was no easy way to change that.

Note: rclone global-flags can't be configured in the config file,
so this uses the environment variable approach.

references:
- https://rclone.org/docs/#logging
- https://rclone.org/docs/#v-vv-verbose

If no value is given, use the implicit default of rclone instead of redefining it through the options

modules/programs/rclone.nix

@@ -111,6 +111,23 @@ in
                       options = {
                         enable = lib.mkEnableOption "this mount";
 
+                        logLevel = lib.mkOption {
+                          type = lib.types.nullOr (
+                            lib.types.enum [
+                              "ERROR"
+                              "NOTICE"
+                              "INFO"
+                              "DEBUG"
+                            ]
+                          );
+                          default = null;
+                          example = "INFO";
+                          description = ''
+                            Set the log-level.
+                            See: https://rclone.org/docs/#logging
+                          '';
+                        };
+
                         mountPoint = lib.mkOption {
                           type = lib.types.str;
                           default = null;
@@ -348,12 +365,13 @@ in
                     Environment = [
                       # fusermount/fusermount3
                       "PATH=/run/wrappers/bin"
-                    ];
+                    ]
+                    ++ lib.optional (mount.logLevel != null) "RCLONE_LOG_LEVEL=${mount.logLevel}";
+
                     ExecStartPre = "${pkgs.coreutils}/bin/mkdir -p ${mount.mountPoint}";
                     ExecStart = lib.concatStringsSep " " [
                       (lib.getExe cfg.package)
                       "mount"
-                      "-vv"
                       (lib.cli.toGNUCommandLineShell { } mount.options)
                       "${remote-name}:${mount-path}"
                       "${mount.mountPoint}"