Scope dashboard GET endpoints by workspace

[alex-mcgovern]

Unsure on the best implementation here, whether it is:

• leave existing API contract untouched, and implicitly filter prompts / messages by the active workspace ID
• add optional query parameter to filter the prompts / messages by a provided workspace ID

[lukehinds]

👀 @JAORM @aponcedeleonch

[JAORMX]

@alex-mcgovern given the recent changes, is this still valid?

[JAORMX]

This was done already