Don't warn about unexpected properties in extension manifests #491
Description
BetterBird, like Thunderbird, does not currently offer a robust extension loading mechanism. Instead, extensions have to pretty much "load themselves" using a script.
Naturally, extension authors would benefit for at least that script being a generic loader rather than completely bespoke. However - for that to happen, the extension-specific information for it to operate need to be stored in the manifest file.
... which is one reason of many when extension authors have "custom" fields in their manifest.json files, which TB/BB don't know about.
Given this state of affairs w.r.t. extension loading, it does not seem appropriate for the TB/BB extension loader to litter the console with gobs and gobs of messages about such properties, e.g.:
1760989271297 addons.webextension.{54e72d7b-ed31-4736-854f-f517358f21ee} WARN Loading extension '{54e72d7b-ed31-4736-854f-f517358f21ee}': Reading manifest: Warning processing chrome_injectors: An unexpected property was found in the WebExtension manifest.
Just make those go away. If we absolutely must keep these warnings say for some debugging purpose, then - let their issue be controlled by some preference.
This does not seem to be reported on bugzilla.mozilla.org , and frankly - I doubt it would be very well received by the anti-extension'ish clique there. Doing this would make BB a little more friendly to extension developers - and of course, who doesn't want a cleaner Error Console?