added create channel to sql and browse channels page

src-tauri/prisma/migrations/20230410024403_add_channel/migration.sql

@@ -0,0 +1,12 @@
+-- CreateTable
+CREATE TABLE "Channel" (
+    "id" INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    "eventId" TEXT NOT NULL,
+    "content" TEXT NOT NULL
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "Channel_eventId_key" ON "Channel"("eventId");
+
+-- CreateIndex
+CREATE INDEX "Channel_eventId_idx" ON "Channel"("eventId");