[bug#67512] Feedback for Librewolf package

[Romain Garbage]

Hello,

I tested the v5 of the patch series, applied on guix master 0547fe862c.

Both patches apply and compile cleanly.

I then launched Librewolf through `./pre-inst-env guix shell librewolf -- 
librewolf`.

I got an error window with the following error message: "Configuration Error: 
Failed to read the configuration file. Please contact your system 
administrator."

and the following error messages in console:

```
JavaScript error: librewolf.cfg, line 545: SyntaxError: missing ) in 
parenthetical
JavaScript warning: resource://services-settings/Utils.sys.mjs, line 57: 
unreachable code after return statement
console.error: "formatURLPref: Couldn't get pref: " 
"startup.homepage_welcome_url.additional"
console.error: "Ignoring protocol handler for mailto without a uriTemplate!"
console.error: ({})
JavaScript error: resource://activity-stream/lib/TelemetryFeed.jsm, line 1066: 
Error: Failed to load chrome://pocket/content/pktApi.sys.mjs
JavaScript error: resource://gre/modules/PromiseWorker.sys.mjs, line 96: Error: 
Could not get children of 
file(/home/romain/.librewolf/rhx67hr4.default/thumbnails) because it does not 
exist
console.error: "about:home startup cache construction failed:" (new 
TypeError("sectionOrder is undefined", 
"resource://activity-stream/data/content/activity-stream.bundle.js", 7802))
console.error: "update.locale" " file doesn't exist in either the application 
or GRE directories"
console.error: services.settings: 
  main/search-config Signature failed  InvalidSignatureError: Invalid content 
signature (main/search-config) using 
'remote-settings.content-signature.mozilla.org-2024-04-09-14-36-39.chain'
console.error: services.settings: 
  main/search-config local data was corrupted
console.warn: services.settings: main/search-config Signature verified failed. 
Retry from scratch
```

After closing the error window, the browser launched properly and could be used 
to browse the web.

I closed it and launched it again and got the same error window, then the 
browser started again (same behaviour).

I tried to install an add-on from `about:addons`, I got redirected to 
https://addons.mozilla.org eventhough gnuzilla.gnu.org is mentioned in the 
search bar. 
The Firefox addons website doesn't recognise Librewolf as a Firefox compatible 
browser and suggests to install Firefox instead of the addon installation.

I don't know if these issues are related to the guix package, although I have 
been using Librewolf in NixOS during one year as a daily driver and never ran 
into these issues.

If you need more testing or details, feel free to ask :)

Have a nice day,
Romain