[Due for payment 2025-04-10] Remove all NSQS Code

[yuwenmemon]

The NSQS Project is ending early and we won't be moving forward with implementation. Let's remove all the code we wrote as a part of these issues:

• [Due for payment 2025-02-18] NSQS Frontend components: Multi-connection selector #55495
• NSQS Frontend components: NSQS setup (OAuth Flow) #55496
• NSQS Frontend components: Import/Export/Advanced Settings #55497
• [Due for payment 2025-03-03] NSQS Frontend Components: Update approvalAccount selector to be "Payment Account" on the Export Tab #56802

@s77rt @zsgreenwald

[maddylewis]

@yuwenmemon is @dukenv0307 owed the standard $250 for this issue? #56802 (comment)

[rayane-d]

@yuwenmemon please assign me here. Thanks