Add Empty State to Workspace list

[jenny-s51]

When filters are applied and no items match the criteria, we should display a consistent empty state message (similar to the one added in the Workspace Kinds table). This will provide clarity for users when no filter results are found.

E.g.:

This is a follow up for #237 cc @liavweiss

[jenny-s51]

/area frontend

[jenny-s51]

/area v2

[jenny-s51]

/assign @liavweiss

[ederign]

/retitle Add Empty State to Workspace list