[✨FEATURE] Add Flutter support

[DugarRishab]

Description

Add flutter support to omni-clied. Use the Developer Manual to quickly develop this feature.

Guidelines overview

• Make a template: Make general templates according to Developer Manual. Follow this manual strictly to make omni the most efficient.
• Think of all general templates: make their general templates.
• Design: keep the design simple. Use Material-UI for design components. Follow best Flutter practices.
• Complete it: remember, the code should be production ready, except some config changes, everything else should already be ready. The user should be able to deploy it with just few config changes.
• Test: Do through testing before PR

Checklist (just a reference, feel free to add to it)

• Make a Login/signup page
• Use google oAuth. (dont worry about the backend part, it is already present in other libs of omni)
• Make a bottom navigation bar
• Implement proper routing
• Make a side menubar controlled by a hamburger menu
• Implement proper error handling

Important:

Read Developer Manual before anything else.