experiment api, fixing userId, deviceId, flexible rollout strategy

Signed-off-by: chandresh pancholi <chandresh.pancholi@navi.com>

litmus-liquibase/src/main/resources/db/changelog/202110061546-create-experiment-table.sql

@@ -0,0 +1,23 @@
+--liquibase formatted sql
+
+--changeset author:chandresh id:202110061546
+CREATE TABLE experiments (
+    id SERIAL PRIMARY KEY,
+    experiment_id varchar(36) NOT NULL,
+    name varchar(100) NOT NULL,
+    description text NOT NULL,
+    enabled boolean,
+    archived boolean,
+    strategies jsonb,
+    variants jsonb,
+    experiment_type varchar(100) NOT NULL,
+    start_time timestamp,
+    end_time timestamp,
+    version BIGINT,
+    created_at timestamp,
+    updated_at timestamp
+);
+
+
+CREATE INDEX idx_experiment_id ON experiments(experiment_id);
+CREATE INDEX idx_experiment_name ON experiments(name);