[FC] Prepares integrity on first sync call

[carlosmuvi-stripe]

Summary

Call Integrity#prepare on Activity A (FinancialConnectionsSheetActivity) and reuse the same Integrity instance in Activity B (FinancialConnectionsNativeActivity) when generating tokens.

Motivation

https://docs.google.com/document/d/1joKz5UZHLVazmecfMHbq6gB6n4wj5u8To6AtqYgq_tc/edit?tab=t.0#heading=h.cz1xkpga7giy

Testing

• Manually verified
• Added error tracking for failed integrity checks

[carlosmuvi-stripe]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• [FC] Add app verification to signup flows (Networking+ID) #9830
• [FC] Updates lookup call to use mobile endpoint on verified flows #9820
• [FC] Sends supports_app_verification to sync call when Integrity available #9819
• [FC] Prepares integrity on first sync call #9818 👈 (View in Graphite)
• [FC] Adds ActivityRetainedScope and broader singleton component #9821
• master

This stack of pull requests is managed by Graphite. Learn more about stacking.

[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 MiB │     2 MiB │  0 B │   4.1 MiB │   4.1 MiB │  0 B 
     arsc │     1 MiB │     1 MiB │  0 B │     1 MiB │     1 MiB │  0 B 
 manifest │   2.3 KiB │   2.3 KiB │  0 B │     8 KiB │     8 KiB │  0 B 
      res │ 301.8 KiB │ 301.8 KiB │  0 B │ 455.5 KiB │ 455.5 KiB │  0 B 
   native │   6.2 MiB │   6.2 MiB │  0 B │  15.8 MiB │  15.8 MiB │  0 B 
    asset │   7.1 KiB │   7.1 KiB │  0 B │   6.9 KiB │   6.9 KiB │  0 B 
    other │  90.2 KiB │  90.2 KiB │  0 B │ 170.3 KiB │ 170.3 KiB │  0 B 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
    total │   9.6 MiB │   9.6 MiB │  0 B │  21.5 MiB │  21.5 MiB │  0 B 

 DEX     │ old   │ new   │ diff      
─────────┼───────┼───────┼───────────
   files │     1 │     1 │ 0         
 strings │ 19970 │ 19970 │ 0 (+0 -0) 
   types │  6191 │  6191 │ 0 (+0 -0) 
 classes │  4982 │  4982 │ 0 (+0 -0) 
 methods │ 29769 │ 29769 │ 0 (+0 -0) 
  fields │ 17540 │ 17540 │ 0 (+0 -0) 

 ARSC    │ old  │ new  │ diff 
─────────┼──────┼──────┼──────
 configs │  164 │  164 │  0   
 entries │ 3622 │ 3622 │  0

APK

   compressed    │   uncompressed   │                        
──────────┬──────┼───────────┬──────┤                        
 size     │ diff │ size      │ diff │ path                   
──────────┼──────┼───────────┼──────┼────────────────────────
 28.4 KiB │ +2 B │  62.9 KiB │  0 B │ ∆ META-INF/CERT.SF     
 25.3 KiB │ -2 B │  62.8 KiB │  0 B │ ∆ META-INF/MANIFEST.MF 
──────────┼──────┼───────────┼──────┼────────────────────────
 53.7 KiB │  0 B │ 125.7 KiB │  0 B │ (total)