Ensure finished events are only sent once for payment confirmation

[toluo-stripe]

Summary

Some PMs have many more 'finished' events than 'started' events (e.g. us_bank_account). Every 'confirm' call should send exactly 1 finished event at the end of the flow, matching the single time the SDK reports the final result to the merchant.

Motivation

https://jira.corp.stripe.com/browse/RUN_MOBILESDK-4730

Testing

• Added tests
• Modified tests
• Manually verified

Screenshots

Before	After
before screenshot	after screenshot

Changelog

[github-actions]

Diffuse output:

OLD: paymentsheet-example-release-master.apk (signature: V1, V2)
NEW: paymentsheet-example-release-pr.apk (signature: V1, V2)

          │          compressed           │        uncompressed        
          ├───────────┬───────────┬───────┼──────────┬──────────┬──────
 APK      │ old       │ new       │ diff  │ old      │ new      │ diff 
──────────┼───────────┼───────────┼───────┼──────────┼──────────┼──────
      dex │   4.6 MiB │   4.6 MiB │ -26 B │ 10.2 MiB │ 10.2 MiB │ +8 B 
     arsc │   2.6 MiB │   2.6 MiB │   0 B │  2.6 MiB │  2.6 MiB │  0 B 
 manifest │   5.5 KiB │   5.5 KiB │   0 B │ 29.2 KiB │ 29.2 KiB │  0 B 
      res │ 928.5 KiB │ 928.5 KiB │   0 B │  1.5 MiB │  1.5 MiB │  0 B 
   native │ 949.9 KiB │ 949.9 KiB │   0 B │  2.5 MiB │  2.5 MiB │  0 B 
    asset │  24.8 KiB │  24.8 KiB │  +1 B │   45 KiB │   45 KiB │ +1 B 
    other │ 193.9 KiB │ 193.9 KiB │  -9 B │  366 KiB │  366 KiB │  0 B 
──────────┼───────────┼───────────┼───────┼──────────┼──────────┼──────
    total │   9.2 MiB │   9.2 MiB │ -34 B │ 17.1 MiB │ 17.1 MiB │ +9 B 

         │         raw          │          unique           
         ├───────┬───────┬──────┼───────┬───────┬───────────
 DEX     │ old   │ new   │ diff │ old   │ new   │ diff      
─────────┼───────┼───────┼──────┼───────┼───────┼───────────
   files │     2 │     2 │    0 │       │       │           
 strings │ 50438 │ 50438 │    0 │ 47875 │ 47875 │ 0 (+1 -1) 
   types │ 18080 │ 18080 │    0 │ 16906 │ 16906 │ 0 (+0 -0) 
 classes │ 14275 │ 14275 │    0 │ 14275 │ 14275 │ 0 (+0 -0) 
 methods │ 71163 │ 71163 │    0 │ 69409 │ 69409 │ 0 (+0 -0) 
  fields │ 47398 │ 47398 │    0 │ 46558 │ 46558 │ 0 (+0 -0) 

 ARSC    │ old  │ new  │ diff 
─────────┼──────┼──────┼──────
 configs │  242 │  242 │  0   
 entries │ 6244 │ 6244 │  0

APK

    compressed     │   uncompressed   │                               
───────────┬───────┼───────────┬──────┤                               
 size      │ diff  │ size      │ diff │ path                          
───────────┼───────┼───────────┼──────┼───────────────────────────────
   4.3 MiB │ -27 B │   9.5 MiB │ +8 B │ ∆ classes.dex                 
  53.5 KiB │ -14 B │ 118.6 KiB │  0 B │ ∆ META-INF/CERT.SF            
  50.4 KiB │  +4 B │ 118.5 KiB │  0 B │ ∆ META-INF/MANIFEST.MF        
   8.7 KiB │  +1 B │   8.6 KiB │ +1 B │ ∆ assets/dexopt/baseline.prof 
 275.5 KiB │  +1 B │ 667.7 KiB │  0 B │ ∆ classes2.dex                
   1.2 KiB │  +1 B │   1.2 KiB │  0 B │ ∆ META-INF/CERT.RSA           
───────────┼───────┼───────────┼──────┼───────────────────────────────
   4.7 MiB │ -34 B │  10.4 MiB │ +9 B │ (total)

DEX

STRINGS:

   old   │ new   │ diff      
  ───────┼───────┼───────────
   47875 │ 47875 │ 0 (+1 -1) 
  
  + ~~R8{"backend":"dex","compilation-mode":"release","has-checksums":false,"min-api":21,"pg-map-id":"b10b446","r8-mode":"full","version":"8.8.34"}
  
  - ~~R8{"backend":"dex","compilation-mode":"release","has-checksums":false,"min-api":21,"pg-map-id":"fe15d0b","r8-mode":"full","version":"8.8.34"}