Conversation history empty state

[rebeccaalpert]

RHDH is looking for an empty state for conversation history.

Related design issue: patternfly/patternfly-design-kit#784

For search empty state, use https://www.patternfly.org/components/empty-state#no-match-found.

[kaylachumley]

@rebeccaalpert updated copy for design:

Empty state for no search results found:

Empty state for no conversation history: