Add PaymentConfirmationMediator & PaymentConfirmationRegistry

[samer-stripe]

Summary

Adds PaymentConfirmationMediator to mediate payment confirmation types and an accompanying PaymentConfirmationRegistry type to define all the payment confirmation types and create mediators from.

Motivation

Helps move all the ConfirmationOption and Launcher abstractions into a mediator to manage the definitions. Following this PR, we can start slowly moving all the internal definitions of the handler into their own definitions then make the registry a parameter of the handler.

Testing

• Added tests
• Modified tests
• Manually verified

[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 │   1.9 MiB │   1.9 MiB │   0 B │     4 MiB │     4 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 │ 301.5 KiB │ 301.5 KiB │   0 B │   455 KiB │   455 KiB │  0 B 
   native │   6.2 MiB │   6.2 MiB │   0 B │  15.8 MiB │  15.8 MiB │  0 B 
    asset │   6.8 KiB │   6.8 KiB │   0 B │   6.6 KiB │   6.6 KiB │  0 B 
    other │  85.5 KiB │  85.5 KiB │ -11 B │ 158.7 KiB │ 158.7 KiB │  0 B 
──────────┼───────────┼───────────┼───────┼───────────┼───────────┼──────
    total │   9.5 MiB │   9.5 MiB │ -11 B │  21.4 MiB │  21.4 MiB │  0 B 

 DEX     │ old   │ new   │ diff      
─────────┼───────┼───────┼───────────
   files │     1 │     1 │ 0         
 strings │ 20252 │ 20252 │ 0 (+0 -0) 
   types │  6082 │  6082 │ 0 (+0 -0) 
 classes │  4886 │  4886 │ 0 (+0 -0) 
 methods │ 29463 │ 29463 │ 0 (+0 -0) 
  fields │ 17389 │ 17389 │ 0 (+0 -0) 

 ARSC    │ old  │ new  │ diff 
─────────┼──────┼──────┼──────
 configs │  164 │  164 │  0   
 entries │ 3608 │ 3608 │  0

APK

    compressed    │   uncompressed   │                        
──────────┬───────┼───────────┬──────┤                        
 size     │ diff  │ size      │ diff │ path                   
──────────┼───────┼───────────┼──────┼────────────────────────
 28.3 KiB │  -7 B │  62.6 KiB │  0 B │ ∆ META-INF/CERT.SF     
  1.2 KiB │  -2 B │   1.2 KiB │  0 B │ ∆ META-INF/CERT.RSA    
 25.1 KiB │  -2 B │  62.5 KiB │  0 B │ ∆ META-INF/MANIFEST.MF 
──────────┼───────┼───────────┼──────┼────────────────────────
 54.6 KiB │ -11 B │ 126.3 KiB │  0 B │ (total)

[samer-stripe]

The handler used to return Payment for IntentConfirmationDefinition which is the more accurate error type to return. Updated the definition to do this as well.

[samer-stripe]

In reality, PaymentSheet should be unaware of this. When we create a fake handler, we should update all the tests to test the interactions with the handler rather than the whole confirmation flow. That should be tested in a more integrated style.

[samer-stripe]

This is a pretty big PR that primarily from the added tests (test code accounts for ~600 lines). I can look into breaking it up into multiple PRs (one for the mediator, one for the registry) if that's easier to read but would just be adding placeholder code that would be immediately removed after merging the registry. There are some smaller changes that I can pull out of this PR but won't make of a dent to this PR size.

[samer-stripe]

@jaynewstrom-stripe I think you mentioned potentially injecting this attribute. I could have another mediator object that is shared between PaymentSheet and IntentConfirmationDefinition that is able to push this value into the object for PaymentSheet to grab afterwards.

Other option is to have PaymentConfirmationMetadata where we can store attributes like this and use.