Add escape support to templates for custom commands

### Is your feature request related to a problem? Please describe.
sometimes in a template `| quote` isn't enough, for example
`command: 'git commit --message "{{.Form.Type}}{{ if .Form.Scope }}({{ .Form.Scope }}){{ end }}{{.Form.Breaking}}: {{.Form.Message }}"'` will break if .Form.Message contains `"`

### Describe the solution you'd like
like we have `| quote` would be nice to have `| escape` or something similar (maybe a replace?) so we can escape quotes

### Describe alternatives you've considered
Alternatively, something like [sprig](https://masterminds.github.io/sprig/) could be useful

### Additional context

Start by tracing how lazygit parses templates for custom commands and where the existing `quote` function is registered or tested. Define the intended behavior for an `escape`-style helper, especially when the message contains quotes, then add coverage showing that the rendered command remains valid.

Written by the indexing model from the issue text.