Add a --panicOnWarning flag

[bep]

This issue is especially targeted at deprecation warnings. These textual references without a file/template context (filename, line number) is sometimes very hard to debug. It would be much nicer if I could do hugo server --panicOnWarning and just iterate until the warnings go away.

We should also print that flag as part of the deprecation message.

/cc @jmooring

[carlinmack]

Perhaps intentional but this flag does not panic on WARN

hugo --panicOnWarning
Start building sites …
hugo v0.92.0-B3549403+extended linux/amd64 BuildDate=2022-01-12T08:23:18Z VendorInfo=gohugoio
WARN 2022/01/12 23:07:10 .File.TranslationBaseName on zero object. Wrap it in if or with: {{ with .File }}{{ .TranslationBaseName }}{{ end }}

[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.