[connect] Initialize support for customizing appearance

[lng-stripe]

Summary

Main changes:

• Update Appearance API to enable more flexibility.
• Wire up Example app Appearance setting
• Enable changing Appearance on the Payouts example screen to demonstrate real-time updates

Motivation

https://jira.corp.stripe.com/browse/MXMOBILE-2507

Testing

• [x] Added tests -- only minimally adding tests for now as we're rapidly iterating.
• [ ] Modified tests
• [x] Manually verified

Screenshots

https://github.com/user-attachments/assets/9cd1dcf0-9a64-4d26-9522-5530af800c40

Changelog

[github-actions[bot]]

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 │ +2 B │ 170.3 KiB │ 170.3 KiB │  0 B 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
    total │   9.6 MiB │   9.6 MiB │ +2 B │  21.5 MiB │  21.5 MiB │  0 B 

 DEX     │ old   │ new   │ diff      
─────────┼───────┼───────┼───────────
   files │     1 │     1 │ 0         
 strings │ 19966 │ 19966 │ 0 (+0 -0) 
   types │  6188 │  6188 │ 0 (+0 -0) 
 classes │  4979 │  4979 │ 0 (+0 -0) 
 methods │ 29759 │ 29759 │ 0 (+0 -0) 
  fields │ 17526 │ 17526 │ 0 (+0 -0) 

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

APK

``` compressed │ uncompressed │ ──────────┬──────┼──────────┬──────┤ size │ diff │ size │ diff │ path ──────────┼──────┼──────────┼──────┼──────────────────────── 25.3 KiB │ +5 B │ 62.8 KiB │ 0 B │ ∆ META-INF/MANIFEST.MF 28.5 KiB │ -4 B │ 62.9 KiB │ 0 B │ ∆ META-INF/CERT.SF 1.2 KiB │ +1 B │ 1.2 KiB │ 0 B │ ∆ META-INF/CERT.RSA ──────────┼──────┼──────────┼──────┼──────────────────────── 54.9 KiB │ +2 B │ 127 KiB │ 0 B │ (total) ```