installApk Fails When Run From a Background Isolate

[ImranR98]

Hi, thanks so much for working on this plugin.
I'm getting the following error when running AppInstaller.installApk from a background process (using WorkManager):

PlatformException (PlatformException(installApkBytes, Couldn't install package, null, null))

Call stack:

StandardMethodCodec.decodeEnvelope (/home/imranr/flutter/packages/flutter/lib/src/services/message_codecs.dart:653)
MethodChannel._invokeMethod (/home/imranr/flutter/packages/flutter/lib/src/services/platform_channel.dart:315)
<asynchronous gap> (Unknown Source:0)

It's weird because it works fine in the main foreground process. I thought it might be related to this issue (flutter/flutter#13937) but it seems the fixes for that have already been merged. I even tried using it with the flutter_isolate plugin, no luck.