Draft CustomPaymentMethod API

[samer-stripe]

Summary

Draft CustomPaymentMethod API

Motivation

Add a draft of the API defined in API Review doc in order to work on custom payment methods support.

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 │     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 │ 302.9 KiB │ 302.9 KiB │  0 B │   457 KiB │   457 KiB │  0 B 
   native │   6.2 MiB │   6.2 MiB │  0 B │  15.8 MiB │  15.8 MiB │  0 B 
    asset │   7.4 KiB │   7.4 KiB │  0 B │   7.1 KiB │   7.1 KiB │  0 B 
    other │  95.2 KiB │  95.2 KiB │ -6 B │ 182.4 KiB │ 182.4 KiB │  0 B 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
    total │   9.6 MiB │   9.6 MiB │ -6 B │  21.6 MiB │  21.6 MiB │  0 B 

 DEX     │ old   │ new   │ diff      
─────────┼───────┼───────┼───────────
   files │     1 │     1 │ 0         
 strings │ 20144 │ 20144 │ 0 (+0 -0) 
   types │  6235 │  6235 │ 0 (+0 -0) 
 classes │  5026 │  5026 │ 0 (+0 -0) 
 methods │ 30045 │ 30045 │ 0 (+0 -0) 
  fields │ 17388 │ 17388 │ 0 (+0 -0) 

 ARSC    │ old  │ new  │ diff 
─────────┼──────┼──────┼──────
 configs │  164 │  164 │  0   
 entries │ 3644 │ 3644 │  0

APK

   compressed    │   uncompressed   │                        
──────────┬──────┼───────────┬──────┤                        
 size     │ diff │ size      │ diff │ path                   
──────────┼──────┼───────────┼──────┼────────────────────────
   29 KiB │ -5 B │    64 KiB │  0 B │ ∆ META-INF/CERT.SF     
  1.2 KiB │ -2 B │   1.2 KiB │  0 B │ ∆ META-INF/CERT.RSA    
 25.7 KiB │ +1 B │    64 KiB │  0 B │ ∆ META-INF/MANIFEST.MF 
──────────┼──────┼───────────┼──────┼────────────────────────
 55.8 KiB │ -6 B │ 129.3 KiB │  0 B │ (total)

[samer-stripe]

I don't except this API to change much from the API review doc. Want to add portions of the API so that work on the straightforward internals can begin (fetching from elements/session, rendering, confirmation)