db: Change the DB storage type to NaiveDateTime

The entire internals of the server now work using only NaiveDateTime,
since we know they are all UTC. At the fringes (LDAP, GraphQL, JWT
tokens) we convert back into UTC to make sure we have a clear API.

This allows us to be compatible with Postgres (which doesn't support
DateTime<UTC>, only NaiveDateTime).

This change is backwards compatible since in SQlite with
Sea-query/Sea-ORM, the UTC datetimes are stored without a timezone, as
simple strings. It's the same format as NaiveDateTime.

Fixes #87.

server/src/domain/model/groups.rs

@@ -11,7 +11,7 @@ pub struct Model {
     #[sea_orm(primary_key, auto_increment = false)]
     pub group_id: GroupId,
     pub display_name: String,
-    pub creation_date: chrono::DateTime<chrono::Utc>,
+    pub creation_date: chrono::NaiveDateTime,
     pub uuid: Uuid,
 }
 

server/src/domain/model/jwt_refresh_storage.rs

@@ -11,7 +11,7 @@ pub struct Model {
     #[sea_orm(primary_key, auto_increment = false)]
     pub refresh_token_hash: i64,
     pub user_id: UserId,
-    pub expiry_date: chrono::DateTime<chrono::Utc>,
+    pub expiry_date: chrono::NaiveDateTime,
 }
 
 #[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]

server/src/domain/model/jwt_storage.rs

@@ -11,7 +11,7 @@ pub struct Model {
     #[sea_orm(primary_key, auto_increment = false)]
     pub jwt_hash: i64,
     pub user_id: UserId,
-    pub expiry_date: chrono::DateTime<chrono::Utc>,
+    pub expiry_date: chrono::NaiveDateTime,
     pub blacklisted: bool,
 }
 

server/src/domain/model/password_reset_tokens.rs

@@ -11,7 +11,7 @@ pub struct Model {
     #[sea_orm(primary_key, auto_increment = false)]
     pub token: String,
     pub user_id: UserId,
-    pub expiry_date: chrono::DateTime<chrono::Utc>,
+    pub expiry_date: chrono::NaiveDateTime,
 }
 
 #[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]

server/src/domain/model/users.rs

@@ -18,7 +18,7 @@ pub struct Model {
     pub first_name: Option<String>,
     pub last_name: Option<String>,
     pub avatar: Option<JpegPhoto>,
-    pub creation_date: chrono::DateTime<chrono::Utc>,
+    pub creation_date: chrono::NaiveDateTime,
     pub password_hash: Option<Vec<u8>>,
     pub totp_secret: Option<String>,
     pub mfa_type: Option<String>,