[PR] - Updating dependencies on package and example app

[LuchoTurtle]

closes #236

Here's a list of what this PR does.

• Updated i18n_extensions and fixed gradle files to make the example app run on an Android device. Also repaired iOS files (podfile) so the example app could run as well.
• Updated image_picker.
• Updated string_validator.
• Upgraded device_info_plus. With this upgrade, also updated the file_picker on the example app otherwise dependency versioning wouldn't work. With this update, I've also deleted the generated generated_plugin_registrant.dart, as it's not needed. See https://github.com/fluttercommunity/plus_plugins/issues/1274 for more details.

Updating these dependencies meant I had to make some changes to Gradle files on Android and Podfile on iOS. This is why you'll see changes to these files so they can actually be built and work on real devices (I've tested these updates on both real Android and iOS devices, as well as on the web).

I didn't mess with the pedantic dependency because I don't know how your team wants to lint the code. Because pedantic is deprecated and flutter_lints is the default way of doing this, I kept it for now.

This also closes #238 .

I've added (on https://github.com/visual-space/visual-editor/pull/237/commits/081cca69960c04dda67abc08234ff87f5ea363bd) changes that replaces gallery_saver to gal. This is needed because dependency version solving fails with http otherwise.

I initially made this change from a branch that started from this branch. But decided to cherry-pick the commit into this branch to make it easier to review and merge.

[LuchoTurtle]

I've added a commit for replacing gallery_saver for gal. See the original issue #238 and above for more context.

I've followed a similar strategy as that from https://github.com/CarnegieTechnologies/gallery_saver/blob/master/lib/gallery_saver.dart#L34, so the feature should be intact. I've tested this on both Android and iOS devices and it works.

I'm not handling the exception in case this fails (it just logs the error, so the app doesn't crash). I believe we should show a snackbar (it does already when the operation is successful) with the error. But this involved adding stuff to i18n, hence why I decided against doing this.

[nelsonic]

@LuchoTurtle we know @adrian-moisa is super busy right now, so until this is merged, please use your Fork as the basis for updating the tutorial: https://github.com/dwyl/flutter-wysiwyg-editor-tutorial/issues/3

Ref: https://stackoverflow.com/questions/68185380/how-to-use-a-fork-of-flutter-widgets

We can the go back to using the "official" version when this is merged and published. 👌

[adrian-moisa]

Already fixed in another commit