feat: Bitwarden Secrets provider

[carnei-ro]

adds Bitwarden Secrets
closes #427

This provider uses the Bitwarden SDK Go, which needs GCO enabled and musl-tools to compile (linux), check this doc.

Use ref+bws://<PROJECT_NAME>/<SECRET_NAME> to fetch the secret value.

$ make build
CGO_ENABLED=1 CC=clang CXX=clang++ go build -ldflags '-X main.version=v0.37.3-56-g8a1c52c-dirty -X main.commit=8a1c52c880fe3a40e0c65035b6ab5f8e742b7534' -o bin/vals ./cmd/vals

$ cat myyaml.yaml 
baz:
  mykey:
    simple_secret: ref+bws://vals-test/fooKey
    yaml: |
      ref+bws://vals-test/myYAML
    parsing_yaml_secret: ref+bws://vals-test/myYAML#baz

$ cat myyaml.yaml | bin/vals eval
baz:
  mykey:
    parsing_yaml_secret: qux
    simple_secret: myValue
    yaml: |
      foo: bar
      baz: qux

$ env | grep BWS_
BWS_ORGANIZATION_ID=d2f88df6-REDA-CTED-0000-000000000000
BWS_ACCESS_TOKEN=0.b5a15cb4-REDA-CTED-0000-000000000000.abcdefghijklmnopqrstuvwxyzABCD:aSBsb3ZlIHZhbHMgISAhCg==

The test is passing:

$ go test -run TestValues_BitwardenSecrets_String .
ok      github.com/helmfile/vals        7.151s

[yxxhero]

@zhaque44 this PR broken many build process.