Create Post class (for home page)

[galvinter]

• Friend reviewed a book
• Friend ranked a book (only stars, no text)
• Friend added a book to wishlist
• New book added, be the first to read!
• Specific book recommendation

[AdvaBitan21]

Post class will not be a collection, Post is a helper class so when we will make a recycler view for the fid, we will use a list of Post class.

[AdvaBitan21]

for having documents of added to wish list, we need to have a collection of wish list so im adding class of wish list