Delete AddPaymentMethodActivity from examples

[amk-stripe]

Summary

Delete AddPaymentMethodActivity from examples

Ensured that this didn't leave any dead code behind by using the "analyze > inspect code" tool in Android Studio

Motivation

https://jira.corp.stripe.com/browse/MOBILESDK-2405

Pre-work for deprecating basic integration is to remove our code samples that reference BI

[amk-stripe]

This is a BI-specific test. Since we will be removing BI in a month-ish anyways, I think it's safe to delete this test. We have other tests for Fpx outside of BI, e.g. TestFpx

[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 │   6.5 KiB │   6.5 KiB │  0 B 
    other │  85.5 KiB │  85.5 KiB │ -10 B │ 158.7 KiB │ 158.7 KiB │  0 B 
──────────┼───────────┼───────────┼───────┼───────────┼───────────┼──────
    total │   9.5 MiB │   9.5 MiB │ -10 B │  21.4 MiB │  21.4 MiB │  0 B 

 DEX     │ old   │ new   │ diff      
─────────┼───────┼───────┼───────────
   files │     1 │     1 │ 0         
 strings │ 20244 │ 20244 │ 0 (+0 -0) 
   types │  6082 │  6082 │ 0 (+0 -0) 
 classes │  4886 │  4886 │ 0 (+0 -0) 
 methods │ 29462 │ 29462 │ 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 │  -5 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                    
    271 B │  -1 B │     120 B │  0 B │ ∆ META-INF/version-control-info.textproto 
──────────┼───────┼───────────┼──────┼───────────────────────────────────────────
 54.9 KiB │ -10 B │ 126.4 KiB │  0 B │ (total)

[amk-stripe]

Rationale for deleting this test is the same as for deleting the Fpx test: This is a BI-specific test. Since we will be removing BI in a month-ish anyways, it's safe to delete this test.

We don't have other tests for Netbanking, but we have 0 users: https://hubble.corp.stripe.com/queries/amk/0b2180e2

And since this entry point is deprecated + will be deleted soon + is not mentioned on docs.stripe.com anywhere, I think we are good to just leave this untested.