[Enhancement] Rewrite examples

[AlexV525]

Request Statement

The examples (mostly the Flutter one) might not being well-formed, it can be cover our features as much as possible.

Solution Brainstorm

I wrote a inspect plugin to combine dio and flutter_ume before. The new example could be similar, covering our features as much as possible, and it can even be a HTTP Request app on your phones.

[Shamsudeen12]

@AlexV525 Can I work on this?