fix(llc): Fix attachment upload state uneven progress. (#315)

* feat(llc): Add rate limiter functions.
fix(llc): Fix attachment upload state uneven progress.

Signed-off-by: Sahil Kumar <[email protected]>

* feat(llc): Export `async.dart` and `rate_limit.dart`

Signed-off-by: Sahil Kumar <[email protected]>

* refactor(llc): Replace our `rate_limit` implementation with the dart port of js `lodash` to better handlw `cancel` and `flush` functions.

Signed-off-by: Sahil Kumar <[email protected]>

* fix(UI-Kit): Make android example run on real devices

Signed-off-by: Sahil Kumar <[email protected]>

* fix offline behaviour

Co-authored-by: Salvatore Giordano <[email protected]>

packages/stream_chat_flutter/example/android/build.gradle

@@ -6,7 +6,7 @@ buildscript {
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:4.0.1'
+        classpath 'com.android.tools.build:gradle:3.6.2'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }