Add text IS [NOT] NORMALIZED -> boolean support to SQL and str library

[jqnatividad]

Description

...as the unicode-normalization crate has the required is_ functions.

https://docs.rs/unicode-normalization/latest/unicode_normalization/index.html#functions

Filing a separate feature request as per @alexander-beedie in #20692 now that #20705 is about to be merged.

Can you split out the request for text IS [NOT] [form] NORMALIZED → boolean as a separate Issue? I took a quick look and it seems it will require an update to the upstream sqlparser-rs lib (which I can likely do, but we'll have to wait for the subsequent release of that lib to add support here). Easier to manage as separate Issues so I can close this one and keep the other on my radar👌

[alexander-beedie]

FYI: have prepped a PR for sqlparser-rs with parsing support for IS [NOT] [form] NORMALIZED syntax. See: apache/datafusion-sqlparser-rs#1655.

If/when that merges (and we have implemented the expression equivalent) we can look at integration for Polars SQL.