feat(model): support labels in manifest

[brooksmtownsend]

Feature or Problem

This PR adds supports for serializing the labels in a manifest and validating that they are correct according to the kubernetes label specification, which also matches the OAM specification.

Related Issues

Fixes #249

Release Information

Next wadm

Consumer Impact

Testing

Unit Test(s)

Added unit test to sanity check validation rules.

Acceptance or Integration

Manual Verification

With a manifest:

apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
  name: kvcounter-rust
  annotations:
    version: v0.0.1
    description: "Kvcounter demo in Rust, using the WebAssembly Component Model and WebAssembly Interfaces Types (WIT)"
  labels:
    app.kubernetes.io/name: kvcounter-rust
spec:

The requested spec comes back as (including the label):

➜ nats req "wadm.api.default.model.get.kvcounter-rust" '{}'
17:15:21 Sending request on "wadm.api.default.model.get.kvcounter-rust"
17:15:21 Received with rtt 2.827708ms
{"result":"success","message":"Successfully fetched model kvcounter-rust","manifest":{"apiVersion":"core.oam.dev/v1beta1","kind":"Application","metadata":{"name":"kvcounter-rust","annotations":{"description":"Kvcounter demo in Rust, using the WebAssembly Component Model and WebAssembly Interfaces Types (WIT)","version":"v0.0.1"},"labels":{"app.kubernetes.io/name":"kvcounter-rust"}}

[joonas]

Looks good to me!

[thomastaylor312]

One blocking comment around things to test for. Others are optional

[thomastaylor312]

Super nit: you could just do part.starts_with(char::is_ascii_alphabetic)