Create schema for the API (#28)

* feat(schema): add basic structs for schema

* feat(schema): implement base62 id parsing

* docs(schema): add documentation for schema structs
fix(schema): prevent integer overflow in base62 decoding

* refactor(schema): move ids into submodules, reexport from ids mod

* feat(schema): add random generation of base62 ids
style: run rustfmt

src/models/mod.rs

@@ -1,2 +1,4 @@
 pub mod error;
+pub mod ids;
 pub mod mods;
+pub mod teams;