POC: Integrate basic dashboard layout with live data

What does this MR do and why?

Related to #370556 (closed)

Adds a Product Analytics / Dashboards page on projects (:project/-/product_analytics/dashboards) which shows a Cube.js powered chart with resizable blocks.

This is a more detailed list of the changes:

• Add @jitsu/sdk-js NPM package
• Initialize Jitsu using an async function. With hard-coded credentials
• Create Project/Product Analytics menu item
• Move former Project/Monitor/Product Analytics to Project/Product Analytics/Tabs
• Create Project/Product Analytics/Dashboards
• Add gridstack NPM package
• Add Analytics Dashboards as a Vue app with a basic dashboarding implementation
• Add @cubejs-client/vue NPM package
• Wrap dashboarding logic into reusable components

Screenshots or screen recordings

Dashboard definition

{
  id: 1,
  title: 'Default dashboard',
  charts: [
    {
      id: 1,
      dimensions: { x: 0, y: 0, height: 4, width: 6, minHeight: 4, minWidth: 6 },
      label: 'Users / Time',
      type: 'line',
      // query: this.withFilters(overTimeQueries.Users, 'day'),
      query: {
        measures: ['Sessions.usersCount'],
        timeDimensions: [
          {
            dimension: 'Sessions.sessionStart',
            dateRange: ['2022-07-01T04:00:00.000Z', '2022-09-01T04:00:00.000Z'],
            granularity: 'day',
          },
        ],
      },
      options: {
        xAxis: {
          name: 'Time',
          type: 'time',
          axisLabel: { interval: 0, showMinLabel: false, showMaxLabel: false, align: 'right' },
        },
        yAxis: { name: 'Counts' },
        legend: { show: false },
      },
    },
  ],
},

Dashboards page

How to set up and validate locally

1. Enable the feature flag

   Feature.enable(:product_analytics)

2. Start the Product Analytics DevKit (make sure to connect GDK to your local DevKit).
3. Update Cube.js JWT at app/assets/javascripts/product_analytics/dashboards/components/analytics_dashboard_content.vue:9, with one generated from Cube.js Playground's Security Context options.
4. Browse through the instance to generate session data.
5. Visit any project Product Analytics / Dashboards page, like http://127.0.0.1:3000/flightjs/Flight/-/product_analytics/dashboards.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.