Add strings.RemoveNonPrintableCharacters

### What version of Hugo are you using (`hugo version`)?

$ hugo version
hugo v0.112.3+extended linux/amd64 BuildDate=unknown

### Does this issue reproduce with the latest release? Yes. ### Issue description As far as I can tell, no combination of `plainify`, `safeHTML`, `markdownify`, or `html{Une,E}scape` can fully remove soft hyphens, and at best converts them to `\\\uad`, the only exception I found being `anchorize` which does successfully remove them. I'm not sure which functions out of the above should be able to remove soft hyphens or not (my guess would be `plainify`, since it's meant to "strip HTML tags"), but for now, using `replace .Var "­" ""` is the only way other than `anchorize` that I've found.