Migrate principal store to sqlite

crates/store_sqlite/migrations/4_principals.sql

@@ -0,0 +1,28 @@
+CREATE TABLE principals (
+    id TEXT NOT NULL,
+    displayname TEXT,
+    principal_type TEXT NOT NULL,
+    password_hash TEXT,
+    PRIMARY KEY (id)
+);
+
+CREATE TABLE app_tokens (
+    id TEXT NOT NULL,
+    principal TEXT NOT NULL,
+    token TEXT NOT NULL,
+    displayname TEXT NOT NULL,
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (id),
+    FOREIGN KEY (principal)
+    REFERENCES principals (id) ON DELETE CASCADE
+);
+
+CREATE TABLE memberships (
+    principal TEXT NOT NULL,
+    member_of TEXT NOT NULL,
+    PRIMARY KEY (principal, member_of),
+    CONSTRAINT fk_membership_principal
+    FOREIGN KEY (principal) REFERENCES principals (id) ON DELETE CASCADE,
+    CONSTRAINT fk_membership_member_of
+    FOREIGN KEY (member_of) REFERENCES principals (id) ON DELETE CASCADE
+);