Honor intent SFU as fallback when checkbox and PMO SFU are not set

[cttsai-stripe]

Summary

• Adds fallback to intent setupFutureUsage when user checkbox and payment method options (PMO) SFU are not set
• Applies fallback logic to both confirmation token params and clientContext
• Updates tests with comprehensive coverage for the complete SFU priority chain

Motivation

#11746

Testing

• Added tests
• Modified tests
• Manually verified

Screenshots

Before	After
before screenshot	after screenshot

Changelog

[github-actions]

Diffuse output:

OLD: identity-example-release-base.apk (signature: V1, V2)
NEW: identity-example-release-pr.apk (signature: V1, V2)

          │          compressed          │         uncompressed         
          ├───────────┬───────────┬──────┼───────────┬───────────┬──────
 APK      │ old       │ new       │ diff │ old       │ new       │ diff 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
      dex │   2.1 MiB │   2.1 MiB │  0 B │   4.3 MiB │   4.3 MiB │  0 B 
     arsc │   1.1 MiB │   1.1 MiB │  0 B │   1.1 MiB │   1.1 MiB │  0 B 
 manifest │   2.3 KiB │   2.3 KiB │  0 B │     8 KiB │     8 KiB │  0 B 
      res │ 302.7 KiB │ 302.7 KiB │  0 B │ 456.5 KiB │ 456.5 KiB │  0 B 
   native │   7.9 MiB │   7.9 MiB │  0 B │  19.3 MiB │  19.3 MiB │  0 B 
    asset │   7.7 KiB │   7.7 KiB │  0 B │   7.4 KiB │   7.4 KiB │  0 B 
    other │  95.7 KiB │  95.7 KiB │ +4 B │ 183.5 KiB │ 183.5 KiB │  0 B 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
    total │  11.5 MiB │  11.5 MiB │ +4 B │  25.4 MiB │  25.4 MiB │  0 B 

 DEX     │ old   │ new   │ diff      
─────────┼───────┼───────┼───────────
   files │     1 │     1 │ 0         
 strings │ 20706 │ 20706 │ 0 (+0 -0) 
   types │  6514 │  6514 │ 0 (+0 -0) 
 classes │  5278 │  5278 │ 0 (+0 -0) 
 methods │ 31549 │ 31549 │ 0 (+0 -0) 
  fields │ 18271 │ 18271 │ 0 (+0 -0) 

 ARSC    │ old  │ new  │ diff 
─────────┼──────┼──────┼──────
 configs │  163 │  163 │  0   
 entries │ 3665 │ 3665 │  0

APK

   compressed    │  uncompressed   │                                           
──────────┬──────┼──────────┬──────┤                                           
 size     │ diff │ size     │ diff │ path                                      
──────────┼──────┼──────────┼──────┼───────────────────────────────────────────
    271 B │ +2 B │    120 B │  0 B │ ∆ META-INF/version-control-info.textproto 
 29.2 KiB │ +2 B │ 64.6 KiB │  0 B │ ∆ META-INF/CERT.SF                        
──────────┼──────┼──────────┼──────┼───────────────────────────────────────────
 29.5 KiB │ +4 B │ 64.7 KiB │  0 B │ (total)