## Summary

This PR looks to improve the performance of the newly introduced
`useBrowserFields` implementation. The currently used
`DataViewSpec.fields` isn't performant at scale and is not cached.
Existing code is as follows:
[DataView.toSpec](https://github.com/elastic/kibana/blob/27183690142a5590b4ad72d060c43cad869f3f3c/src/platform/plugins/shared/data_views/common/data_views/data_view.ts#L147)
call as seen
[here](https://github.com/elastic/kibana/blob/27183690142a5590b4ad72d060c43cad869f3f3c/src/platform/plugins/shared/data_views/common/data_views/abstract_data_views.ts#L391-L422),
[here](https://github.com/elastic/kibana/blob/27183690142a5590b4ad72d060c43cad869f3f3c/src/platform/plugins/shared/data_views/common/fields/field_list.ts#L157-L159),
and finally
[here](https://github.com/elastic/kibana/blob/27183690142a5590b4ad72d060c43cad869f3f3c/src/platform/plugins/shared/data_views/common/fields/data_view_field.ts#L438-L440).
While this may not be a significant issue at a few thousand fields, this
does not scale well as the number of fields reaches the tens to hundreds
of thousands.

[Separate PR](elastic#225726) that moves
away from spec usage to pure `DataView` usage

The `useFieldsBrowser` hook is improved by relying directly on the
DataView rather than the DataViewSpec. And there are improvements to the
original sourcerer fieldBrowser calculation. Currently the use of
`memoizeOne` doesn't actually work as the fields object passed to it is
an object and not an array.

A new fieldBrowserManager was introduced that caches based on the scope.
Originally investigated caching via a `WeakMap` to avoid the scenario
where all 4 (current) scopes cache the exact same DataView, but it
looked like references to previously selected dataViews retained a
strong reference in memory, which often led to all N number of selected
dataViews being retained in the cache. The current approach is safer as
the number of cached entries are capped at
`DataViewManagerScopeName.length`

** Relevant configurations **
`xpack.securitySolution.enableExperimental:
['newDataViewPickerEnabled']`

(cherry picked from commit 9a18757)

# Conflicts:
#	x-pack/solutions/security/plugins/security_solution/public/cases/components/ai_for_soc/table.tsx