lib/secrets: trim all right-hand newlines with jq (#237)

Passwords declared in external files can now end with multiple
newlines.

Consider:

        bash> cat --show-all /path/to/secret/password
        hunter2$
        $

        bash> # Before (with rstrimstr):
        bash> jq -n --rawfile passwordContent /path/to/secret/password \
            '{password: ($passwordContent | rtrimstr("\n")), }'
        {
          "password": "hunter2\n"
        }

        bash> # After (with regex):
        bash> jq -n --rawfile passwordContent /path/to/secret/password \
            '{password: ($passwordContent | sub("\n+$"; "")), }'
        {
          "password": "hunter2"
        }

Co-authored-by: Kiri Carlson <kiri@walawren.com>

Author: tmplt

CHANGELOG.md

@@ -8,6 +8,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ### Fixed
 
+- `_secret` pattern not trimming all terminating newlines in decrypted files.
 - qBittorrent potentially starting before `nixflix.serviceDependencies` and thus losing track of downloaded files, lest a recheck was manually forced.
 
 ### Added

lib/secrets/default.nix

@@ -64,7 +64,7 @@ rec {
         else if isSecretRef value then
           {
             flag = "--rawfile ${name}Content ${lib.escapeShellArg (toString value._secret)}";
-            ref = "($" + name + "Content | rtrimstr(\"\\n\"))";
+            ref = "($" + name + "Content | sub(\"\\n+$\"; \"\"))";
           }
         else
           {
@@ -124,7 +124,7 @@ rec {
         let
           jqPath = "." + lib.concatMapStringsSep "" (k: ''["${k}"]'') ref.path;
         in
-        "${jqPath} = ($" + ref.varName + ''Content | rtrimstr("\n"))''
+        "${jqPath} = ($" + ref.varName + ''Content | sub("\n+$"; ""))''
       ) indexedRefs;
     in
     {