WASM compiled functions don't like non-strings in YAML

Original issue URL: https://github.com/kptdev/kpt/issues/3626 Original issue user: https://github.com/wleese Original issue created at: 2022-10-17T13:13:02Z Original issue last updated at: 2022-11-15T21:49:53Z Original issue body: ### Expected behavior

Render should succeed regardless of "123" or 123 values in yaml.

Actual behavior

Package "numbers":
[RUNNING] WASM "eu.gcr.io/bolcom-stg-bb8-infra-6e4/set-namespace:unstable"
panic: ValueOf: invalid value

goroutine 6 [running]:
syscall/js.ValueOf({0xcb960, 0x119ed80})
    /usr/local/go/src/syscall/js/js.go:208 +0xf7
syscall/js.Value.Set({{}, 0x7ff8000100000012, 0x1140690}, {0x1a8ec8, 0x6}, {0xcb960, 0x119ed80})
    /usr/local/go/src/syscall/js/js.go:303 +0x8
syscall/js.handleEvent()
    /usr/local/go/src/syscall/js/func.go:95 +0x27
[FAIL] "eu.gcr.io/bolcom-stg-bb8-infra-6e4/set-namespace:unstable" in 0s
Error: wrong Node Kind for  expected: MappingNode was ScalarNode: value: {s(<nil>}

Information

kptfile

apiVersion: kpt.dev/v1
kind: Kptfile
metadata:
  name: numbers
  annotations:
    config.kubernetes.io/local-config: "true"
info:
  description: sample description
pipeline:
  mutators:
  - image: eu.gcr.io/xxxx/set-namespace:unstable
    configPath: package-context.yaml

set-namespace is compiled to WASM.

package-context.yaml

apiVersion: v1
kind: ConfigMap
metadata:
  name: kptfile.kpt.dev
  annotations:
    config.kubernetes.io/local-config: "true"
data:
  name: example
  namespace: 1234

Saw the behavior with apply-replacements as well.

Steps to reproduce the behavior

Use the above resources with a WASM compiled function such as set-namespace.

Original issue comments: Comment user: https://github.com/wmuizelaar Comment created at: 2022-10-17T18:40:02Z Comment last updated at: 2022-10-17T18:40:02Z Comment body: To add to this: I can also reproduce this without using the WASM function, and in above example only chante the mutator-image to gcr.io/kpt-fn/set-namespace:v0.4.1

Package "kpt-test":
[RUNNING] "gcr.io/kpt-fn/set-namespace:v0.4.1"
[FAIL] "gcr.io/kpt-fn/set-namespace:v0.4.1" in 800ms
  Results:
    [error]: SubObject has unmatched field type: `data/namespace
  Stderr:
    "failed to evaluate function: SubObject has unmatched field type: `data/namespace"
  Exit code: 1

This seems to be caused by YAML automatically thinking that a numeric field should be considered as pure numeric. Should this always be casted as a string (and is this therefore a bug), or should we as a user make sure that when there is a potential for all numeric fields, that we quote those values to enforce them to be read as a string?

nephio-project / nephio