feat(backend): add handlePartialPayment for incoming payments

[njlie]

Changes proposed in this pull request

• Adds a handlePartialPayment service call to the incoming payment service, to be called when encrypted data is transmitted through an ILP stream.

Context

Fixes RAF-1183 and fixes RAF-1184.

Checklist

• Related issues linked using fixes #number
• Tests added/updated
• Make sure that all checks pass
• Bruno collection updated (if necessary)
• Documentation issue created with user-docs label (if necessary)
• OpenAPI specs updated (if necessary)

[github-actions]

🚀 Performance Test Results

Test Configuration:

• VUs: 4
• Duration: 1m0s

Test Metrics:

• Requests/s: 40.73
• Iterations/s: 13.58
• Failed Requests: 0.00% (0 of 2450)

📜 Logs

> [email protected] run-tests:testenv /home/runner/work/rafiki/rafiki/test/performance
> ./scripts/run-tests.sh -e test "-k" "-q" "--vus" "4" "--duration" "1m"

Cloud Nine GraphQL API is up: http://localhost:3101/graphql
Cloud Nine Wallet Address is up: http://localhost:3100/
Happy Life Bank Address is up: http://localhost:4100/
cloud-nine-wallet-test-backend already set
cloud-nine-wallet-test-auth already set
happy-life-bank-test-backend already set
happy-life-bank-test-auth already set
     data_received..................: 884 kB 15 kB/s
     data_sent......................: 1.9 MB 31 kB/s
     http_req_blocked...............: avg=6.94µs   min=1.76µs   med=5.57µs   max=705.38µs p(90)=6.69µs   p(95)=7.27µs  
     http_req_connecting............: avg=657ns    min=0s       med=0s       max=569.82µs p(90)=0s       p(95)=0s      
     http_req_duration..............: avg=97.52ms  min=6.58ms   med=79.82ms  max=559.03ms p(90)=168.09ms p(95)=192.7ms 
       { expected_response:true }...: avg=97.52ms  min=6.58ms   med=79.82ms  max=559.03ms p(90)=168.09ms p(95)=192.7ms 
     http_req_failed................: 0.00%  ✓ 0         ✗ 2450
     http_req_receiving.............: avg=98.19µs  min=28.4µs   med=83.48µs  max=2.41ms   p(90)=123.14µs p(95)=155.31µs
     http_req_sending...............: avg=38.62µs  min=9.87µs   med=29.06µs  max=6.15ms   p(90)=42.05µs  p(95)=55.18µs 
     http_req_tls_handshaking.......: avg=0s       min=0s       med=0s       max=0s       p(90)=0s       p(95)=0s      
     http_req_waiting...............: avg=97.39ms  min=6.44ms   med=79.72ms  max=558.91ms p(90)=167.97ms p(95)=192.59ms
     http_reqs......................: 2450   40.733588/s
     iteration_duration.............: avg=294.14ms min=186.96ms med=272.53ms max=1.09s    p(90)=370.62ms p(95)=397.38ms
     iterations.....................: 817    13.583405/s
     vus............................: 4      min=4       max=4 
     vus_max........................: 4      min=4       max=4