Create content collections for cafe Flutter

[payam-zahedi]

We already have the UI for the #5

What we need to achieve in this issue is to create content collection for Café Flutters
For now, we are using hard coded models, but what we need is to define a collection and use them in home screen and other sections.

Café flutter content collection should have the following properties:

1. title
2. image
3. data and time
4. Google meet link
5. Calendar link
6. YouTube link
7. array of talks

talk model

1. speaker => refrence to member collection
2. talk title
3. short description about talk