[Obs Nav] Create sub-nav hierarchy for stateful and serverless

[paulb-elastic]

There is requirement to change the design of the left navigation, to be based on a second level navigation pane, in place of the current expanding (nested) sections.

This needs to be applied to both stateful and severless (as a reminder, there are already some differences between the menu options available in stateful and serverless, and this will still be the case even with this new layout).

A clickable version of the figma mock up (specifically for stateful) can be found here.

Note that the Platform team (@sebelga) can help point us in the right direction if there are any questions on how this should be implemented.

Acceptance Criteria

• The “switch on new navigation” will still be an opt-in (per space) in stateful, in 8.16 (as is the current behaviour)
  • You opt in via Stack Management > Spaces > Navigation > Set solution view
    • Change from empty/classic, to Observability
  • Note that you don’t opt-in in with serverless as there is only one kind of navigation (the layout of which will be updated with this issue)
• With this change, the sub-navigation will be shown instead of the collapsable/nested view we have currently:
  • By default in serverless
  • In 8.16 in stateful if opted in (i.e. Set solution view == Observability)
• The current single level menu items (like Alerts), do not change
• The hover behaviour for the menus are shown in the figma mockup

⚠️ NOTE that @kkurstak is confirming the use of title/sentence case for the various menu headings and items

Stateful

The navigation options where there are two levels available for stateful are as follows (see figma for mock up) - note these use Sentence case:

• Applications (first level)
  • Applications (main heading in second navigation panel not clickable)
  • Services
  • Traces
  • Dependencies
  • User experience
  • SYNTHETICS (subheading not clickable) - NOTE this has moved under Applications from it’s current top-level position
  • Monitors
  • TLS certificates
• Infrastructure (first level)
  • Infrastructure (main heading in second navigation panel not clickable)
  • Inventory
  • Hosts
  • Metrics explorer
  • UNIVERSAL PROFILING (subheading not clickable)
  • Stacktraces
  • Flamegraphs
  • Functions
• Machine learning (first level)
  • Machine learning (main heading in second navigation panel not clickable)
  • Overview
  • Notifications
  • Memory usage
  • ANOMALY DETECTION (subheading not clickable)
  • Jobs
  • Anomaly explorer
  • Logs anomalies
  • Single metric viewer
  • Settings
  • DATA FRAME ANALYTICS (subheading not clickable)
  • Jobs
  • Results explorer
  • Analytics map
  • MODEL MANAGEMENT (subheading not clickable)
  • Trained models
  • Flamegraphs
  • DATA VISUALIZER (subheading not clickable)
  • File
  • Data view
  • ES|QL
  • Data drift
  • AIOPS LABS (subheading not clickable)
  • Log rate analysis
  • Log pattern analysis
  • Change point detection
• Other tools (first level)
  • Other tools (main heading in second navigation panel not clickable)
  • Logs stream
  • Logs categories
  • Canvas
  • Maps
  • Graph
  • Visualise library
• Management (first level)
  • Management (main heading in second navigation panel not clickable)
  • Integrations
  • Fleet
  • Osquery
  • INGEST (subheading not clickable)
  • Logstash pipelines
  • Ingest pipelines
  • DATA (subheading not clickable)
  • Index management
  • Index lifecycle policies
  • Data set quality
  • Snapshot and restore
  • Rollup jobs
  • Transforms
  • Cross-cluster replication
  • Remote clusters
  • ALERTS AND INSIGHTS (subheading not clickable)
  • Alerts
  • Rules
  • Connectors
  • Reporting
  • Watcher
  • Maintenance windows
  • SECURITY (subheading not clickable)
  • Users
  • Roles
  • API keys
  • Role mapping
  • KIBANA (subheading not clickable)
  • Data views
  • Files
  • Saved objects
  • Tags
  • Search sessions
  • Spaces
  • Advanced settings
  • STACK (subheading not clickable)
  • Upgrade assistant

Serverless

The navigation options where there are two levels available for serverless are as follows:

⚠️ TODO

Breadcrumbs

• Check that breadcrumbs are not affected by the change, and if necessary, raise a follow up to fix them
  • For stateful
  • For serverless