Add unit-tests for rewrite middleware

[gaby]

Completed:

• Fixed panic caused by passing an empty config to rewrite.New()
• Added unit-tests for Filter function.
• Added unit-tests for Regex Rules.
• Added unit-tests for default config
• Coverage report is now at 100% of statements
• Added go 1.19.x to test suite

Results:

ubuntu@ubuntu:~/Desktop/git/fix/rewrite$ go test ./...
ok  	github.com/gofiber/rewrite/v2	0.004s
ubuntu@ubuntu:~/Desktop/git/fix/rewrite$ go test -cover ./...
ok  	github.com/gofiber/rewrite/v2	0.004s	coverage: 100.0% of statements