UI for Add metrics, input, and pipeline columns to Streams Overview

[ousmaneo]

The Streams Overview table does not expose recent stream activity and related entities directly in the list view. Users have to navigate away to inspect
message volume, processing time, associated inputs, and connected/routing pipelines.

Solution

This change adds new Streams Overview columns backed by the stream metrics endpoint and expandable sections for related entities.

Scope

• add stream metrics fetching and context wiring for visible overview columns
• add message count, average processing time, and maximum processing time columns
• add associated inputs, connected pipelines, and routing pipelines columns
• add expandable sections to list related inputs and pipelines with resolved entity titles
• extend overview table/plugin wiring so enterprise and other plugins can request additional metric fields
  /jpd Graylog2/graylog-plugin-enterprise#14379
  related to Frontend for the pluggable entity metrics endpoint (Inputs page) #26094
  part of Add routing and performance columns to Streams table #25929
  /nocl

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have requested a documentation update.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.

[gally47]

Looking good, 2 comments below:

• expanded metric sections can show empty content after their column is hidden.

_

• the new stream metric count cells show 0 badges, unlike existing stream overview section cells. (we agreed with Tully last time to hide those, I'd say only for count cells, for 0ms like processing time we can keep them)

[ousmaneo]

Thank you for the review.

• expanded metric sections can show empty content after their column is hidden.

_

This is the default behaviour of the EntityDataTable expanded sections. If you expand a section then hide the field the expanded section remains open. Can you please create a UI issue for that.

[gally47]

Tested it, LGTM.