added crates to public project, made api structure

backend/public/src/datasources/authors.rs

@@ -0,0 +1,2 @@
+pub struct AuthorsDatasource;
+impl AuthorsDatasource {}

backend/public/src/datasources/comments.rs

@@ -0,0 +1,2 @@
+pub struct CommentsDatasource;
+impl CommentsDatasource {}

backend/public/src/datasources/mod.rs

@@ -0,0 +1,3 @@
+pub mod authors;
+pub mod comments;
+pub mod posts;

backend/public/src/datasources/posts.rs

@@ -0,0 +1,2 @@
+pub struct PostsDatasource;
+impl PostsDatasource {}