Browse metrics page (#47277)

* Add custom image for empty metrics

* Add useFetchMetrics helper

* Copy browse models page to metrics page

* Add route for browse metrics page

* Add useHasMetrics hook

* Add link to browse metrics page to the sidebar

* Simplify MetricsTable component

* Render description markdown in table too

* Add unit tests for browse metrics page

* Remove custom padding

* Fix line height of markdown cell

* Add e2e tests for browse page

* Fix metrics sorting

* Fix types

* Fix column widths and cell padding

* Typo

Co-authored-by: Kamil Mielnik <kamil@kamilmielnik.com>

* Remove name check

* Simplify alphabet

* Remove resetSnowplow

* Use helper to get metric in table

* Use MouseEvent from React directly

* Use --mb-color-icon-primary

* Test ellipsification of description

* Simplify useHasMetrics

* Move useHasMetrics MainNavBar

* Merge sortMetrics and sortModels into sortCards

* Fix metric default description

* Extract SidebarSkeleton to a separate component

* Test sorting via Collection too

* Use ModelTableRow to fix cursor

* Share more components between ModelsTable and MetricsTable

* Use the same simplified structure in ModelsTable as for MetricsTable

* Render block-level elements as inline so ellipsis detection works

* Pick better testid for metric name

* Remove delay

* Avoid type specificty error in sortCards

* Add test for not opening in new tab

* Remove useFetchMetrics defaults

* Fix unit test import

* Test meta-click with cypress

* Add comment on inline markdown elements

* Use model-name test id

* Use correct colors for icon

* Remove delay from browse models page too

* Make meta key in test platform-dependent

* Fix hover color on metrics table

* Add focus styling for celss in the models and metrics table

* Use MarkdownPreview for table cells

* Define --mb-color-icon-primary

* Make the collection link take up the whole height of the cell

* Remove tabIndex from table rows

* Rename ModelsTable.module.css to BrowseTable.module.css

* Rename CardsTable to BrowseTable

* Remove single module.css class in favor of styled components

* Allow customising allowed elements

* Allow forcing all markdown on one line

* Render bold and italics in markdown descriptions and move content onto one line

* Fix legacy tooltip in test

* Make sure getValueForSorting returns a string

* Remove empty file

* Remove icon for metrics in the table

* Remove else statement.

Co-authored-by: Uladzimir Havenchyk <125459446+uladzimirdev@users.noreply.github.com>

* Remove async findBy where possible

* Add github issue link for TODO item

* Disambiguate between getMetricDescription type

* Be explicit with sortModelOrMetric

---------

Co-authored-by: Kamil Mielnik <kamil@kamilmielnik.com>
Co-authored-by: Uladzimir Havenchyk <125459446+uladzimirdev@users.noreply.github.com>