App localization and language controller addition

[sumitra19jha]

What kind of change does this PR introduce?
feature closes #799

Did you add tests for your changes?
Not needed here

If relevant, did you update the documentation?
Not needed here

Summary
App Localization file to load user preferred language file and controller to make sure user can switch language as per their convenience.

Does this PR introduce a breaking change?
No

Other information

[palisadoes]

@dellyjm
@DeltaHarbinger
@TheHazeEffect

Could one of your please take a look at this? It's a GSoC PR

[palisadoes]

@sumitra19jha please resolve the conflict with: lib/views/pages/newsfeed/newsfeed.dart

[DeltaHarbinger]

This seems like a good initial commit for the feature. We may need to remove hard coded values such as the supported languages array, but that may be done at a later date.

[sumitra19jha]

@DeltaHarbinger The hard-coded string is part of issue #800
That is the reason why I have not included it in this PR.
It will be done, once this PR is merged.

[palisadoes]

@sumitra19jha flutter test is not working correctly on your code. This is causing Travis CI to fail.

1. Follow the steps in the GitHub site's Checking out pull requests locally web page.
2. Resolve the conflicts, which appear related to pubspec.yml
3. Resubmit your pull request.

The error can be seen below

[palisadoes]

@sumitra19jha It's a slightly different issue now. Please resolve. We should be close to getting this fixed.

12.01s$ travis_apt_get_update
0.00s
git.checkout
1.35s$ git clone --depth=50 https://github.com/PalisadoesFoundation/talawa.git PalisadoesFoundation/talawa
0.01sDart for Travis-CI is not officially supported, but is community maintained.
Please file any issues using the following link
  https://travis-ci.community/c/languages/dart
and mention `@athomas` and `@a14n` in the issue
$ export PUB_ENVIRONMENT=travis
dart_install
Installing Dart on linux
cache.1
Setting up build cache
$ dart --version
Dart SDK version: 2.13.0 (stable) (Wed May 12 12:45:49 2021 +0200) on "linux_x64"
install.1
15.21s$ git clone https://github.com/flutter/flutter.git -b stable
install.2
34.18s$ ./flutter/bin/flutter doctor
3.85s$ ./flutter/bin/flutter test
Running "flutter pub get" in talawa...                                 ⡿       ⣽       ⣯Because every version of flutter_driver from sdk depends on crypto 3.0.1 and graphql >=3.1.0-beta.4 <4.0.0-alpha.0 depends on crypto ^2.1.3, flutter_driver from sdk is incompatible with graphql >=3.1.0-beta.4 <4.0.0-alpha.0.
And because graphql_flutter >=3.1.0 <4.0.0-alpha.0 depends on graphql ^3.1.0, flutter_driver from sdk is incompatible with graphql_flutter >=3.1.0 <4.0.0-alpha.0.
So, because talawa depends on both graphql_flutter ^3.1.0 and flutter_driver any from sdk, version solving failed.
                                       ---- Log transcript ----
FINE: Pub 2.13.0
MSG : Resolving dependencies...
SLVR: fact: talawa is 1.0.0+1

[sumitra19jha]

Yes @palisadoes
I am trying to figure this out

[sumitra19jha]

@palisadoes Done