[chore] [cmd/builder] Require github.com/knadh/koanf submodules (#8301)

Explicitly require `github.com/knadh/koanf/maps` and
`github.com/knadh/koanf/providers/confmap` in go.mod to workaround
ambiguous imports. Otherwise, the command fails with:
```
Error: failed to update go.mod: exit status 1. Output:
go: github.com/open-telemetry/opentelemetry-collector-contrib/cmd/otelcontribcol imports
	github.com/open-telemetry/opentelemetry-collector-contrib/connector/countconnector imports
	go.opentelemetry.io/collector/confmap imports
	github.com/knadh/koanf/maps: ambiguous import: found package github.com/knadh/koanf/maps in multiple modules:
	github.com/knadh/koanf v1.5.0 (/Users/danoshin/go/pkg/mod/github.com/knadh/[email protected]/maps)
	github.com/knadh/koanf/maps v0.1.1 (/Users/danoshin/go/pkg/mod/github.com/knadh/koanf/[email protected])
go: github.com/open-telemetry/opentelemetry-collector-contrib/cmd/otelcontribcol imports
	github.com/open-telemetry/opentelemetry-collector-contrib/connector/countconnector imports
	go.opentelemetry.io/collector/confmap imports
	github.com/knadh/koanf/providers/confmap: ambiguous import: found package github.com/knadh/koanf/providers/confmap in multiple modules:
	github.com/knadh/koanf v1.5.0 (/Users/danoshin/go/pkg/mod/github.com/knadh/[email protected]/providers/confmap)
	github.com/knadh/koanf/providers/confmap v0.1.0 (/Users/danoshin/go/pkg/mod/github.com/knadh/koanf/providers/[email protected])

make: *** [genotelcontribcol] Error 1
```

cmd/builder/internal/builder/templates/go.mod.tmpl

@@ -23,6 +23,11 @@ require (
 	go.opentelemetry.io/collector v{{.Distribution.OtelColVersion}}
 )
 
+require (
+	github.com/knadh/koanf/maps v0.1.1 // indirect
+	github.com/knadh/koanf/providers/confmap v0.1.0 // indirect
+)
+
 {{- range .Connectors}}
 {{if ne .Path ""}}replace {{.GoMod}} => {{.Path}}{{end}}
 {{- end}}