[Meta] Migrate to Common Platform SideNav Components (SharedUX w/assist from Threat Hunting)

[petrklapka]

Context:

For the internal preview release of Serverless, the Security Solution shipped with a different SideNav implementation from the Search and Observability solutions. For the Public Gated Preview, leadership has asked that we work toward a cohesive look and feel. The first step in this effort is to have all three solutions based on the same “common” SideNav component.

While conversations and design continue around look and feel, SharedUX aims to work with Serverless Threat Hunting Team to provide an MVP implementation of the common SideNav that meets the Security solutions minimal requirements, and to achieve the use of a single SideNav for Public Gated Preview. That implementation will then be further evolved to refine look and feel across all solutions.

Requirements:

1. The common SideNav component shall support a sub panel (aka “Flyout) so Security customers do not experience too large a shift in their workflows and usage patterns.
2. All serverless solutions shall use a single SideNav component implementation by the Nov. 15th Public Gated Preview
3. Development shall be complete by ~October 25th to allow for sufficient testing and deployment to customers by Nov. 15th.

Tasks

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1. Extracts Panel component from Security SideNav for reuse in Common SideNav
2. Add temporary style in the EuiCollapsibleNavBeta PR branch to hide the "dock" when the side nav is collapsed.
3. Add support for Panel (aka Flyouts) to Common SideNav: PR [Serverless] Add panels to side nav #167774
4. Consume the common SideNav in Security Solution PR [Security Solution] Enable shared-ux nav #169499
5. Remove temporary style: PR [Serverless nav] Accordion auto-expand state + polish work #169651

[tsullivan]

Update: @sebelga has completed PR #167774 which brings side panel possibilities into the Shared UX component

[tsullivan]

@petrklapka it looks like this issue is completed! WDYT?

[petrklapka]

Why sir, I believe it is!