Add strcase (#5487)

The strcase and bytcase libraries provide efficient case-insensitive
search functions that are Unicode aware and are a drop-in replacement
for the strings/bytes packages.

Docs: https://pkg.go.dev/github.com/charlievieth/strcase@master
Report: https://goreportcard.com/report/github.com/charlievieth/strcase
Coverage: https://app.codecov.io/github/charlievieth/strcase

README.md

@@ -1826,6 +1826,7 @@ _Libraries for working with strings._
 - [caps](https://github.com/chanced/caps) - A case conversion library.
 - [go-formatter](https://gitlab.com/tymonx/go-formatter) - Implements **replacement fields** surrounded by curly braces `{}` format strings.
 - [gobeam/Stringy](https://github.com/gobeam/Stringy) - String manipulation library to convert string to camel case, snake case, kebab case / slugify etc.
+- [strcase](https://github.com/charlievieth/strcase) - Case-insensitive implementation of the standard library's strings/bytes packages.
 - [strutil](https://github.com/ozgio/strutil) - String utilities.
 - [sttr](https://github.com/abhimanyu003/sttr) - cross-platform, cli app to perform various operations on string.
 - [xstrings](https://github.com/huandu/xstrings) - Collection of useful string functions ported from other languages.