Migrate from `go-yaml/yaml` to `goccy/go-yaml`

## Description

The YAML parser we're using (i.e., [go-yaml/yaml](https://github.com/go-yaml/yaml), as `gopkg.in/yaml.v3` module) has recently been archived. A good alternative is [goccy/go-yaml](https://github.com/goccy/go-yaml), which is a Go-idiomatic implementation.

Since this change does not surface to the user experience, an A/C is not applicable.

## Required changes

The YAML parser is only used in one package, which is `internal/yamlmap`. This package implements a strongly-typed wrapper around a YAML data source, and therefore, heavily relies on this particular parser. We will have to rewrite this package. One possible challenge that we might have is that the current parser supports assigning informational tags to YAML nodes, but the new one does not (at least, as I quickly checked).