[MDS] UX Changes for 2.5 Release

[KrooshalUX]

GLOBAL APP TO DO:

• [ ] If an error is present on any page within the application due to a provided endpoint becoming unavailable or authentication failing, present user with a toast message appropriate to the error case

CATCH ALL (@KrooshalUX to update as scope is defined)

• [ ] https://github.com/opensearch-project/ux/issues/27
• [ ] Improvements on empty states
• [ ] Individual messages for all in-line form input boxes
• [ ] Check for errors reaching endpoint when endpoint URL is input (onBlur and onChange)
• [ ] Improved toast messaging for API Create/Update errors (dependent on API changes)
• [ ] Improved input placeholder copy

[KrooshalUX]

Due to engineering priorities changing, these are no longer in scope. I will work with @kristenTian to ensure these line items are accounted for in subsequent releases. Closing for repo cleanliness.