feat: Add template display name (backend) (#4966)

* Rename to nameValidator

* Refactor: NameValid

* Fix: comment

* Define new migration

* Include display_name

* Update typesGenerated.ts

* Update meta

* Adjust tests

* CLI tests

* Fix: audit

* Fix: omitempty

* site: display_name is optional

* unit: TestUsernameValid

* entities.ts: add display_name

* site: TemplateSettingsPage.test.tsx

* Fix: TemplateSettingsForm.tsx

* Adjust tests

* Add comment to display_name column

* Fix: rename

* Fix: make

* Loosen regexp

* Fix: err check

* Fix: template name length

* Allow for whitespaces

* Update migration number

coderd/httpapi/name.go

@@ -0,0 +1,68 @@
+package httpapi
+
+import (
+	"regexp"
+	"strings"
+
+	"github.com/moby/moby/pkg/namesgenerator"
+	"golang.org/x/xerrors"
+)
+
+var (
+	UsernameValidRegex = regexp.MustCompile("^[a-zA-Z0-9]+(?:-[a-zA-Z0-9]+)*$")
+	usernameReplace    = regexp.MustCompile("[^a-zA-Z0-9-]*")
+
+	templateDisplayName = regexp.MustCompile(`^[^\s](.*[^\s])?$`)
+)
+
+// UsernameFrom returns a best-effort username from the provided string.
+//
+// It first attempts to validate the incoming string, which will
+// be returned if it is valid. It then will attempt to extract
+// the username from an email address. If no success happens during
+// these steps, a random username will be returned.
+func UsernameFrom(str string) string {
+	if valid := NameValid(str); valid == nil {
+		return str
+	}
+	emailAt := strings.LastIndex(str, "@")
+	if emailAt >= 0 {
+		str = str[:emailAt]
+	}
+	str = usernameReplace.ReplaceAllString(str, "")
+	if valid := NameValid(str); valid == nil {
+		return str
+	}
+	return strings.ReplaceAll(namesgenerator.GetRandomName(1), "_", "-")
+}
+
+// NameValid returns whether the input string is a valid name.
+// It is a generic validator for any name (user, workspace, template, etc.).
+func NameValid(str string) error {
+	if len(str) > 32 {
+		return xerrors.New("must be <= 32 characters")
+	}
+	if len(str) < 1 {
+		return xerrors.New("must be >= 1 character")
+	}
+	matched := UsernameValidRegex.MatchString(str)
+	if !matched {
+		return xerrors.New("must be alphanumeric with hyphens")
+	}
+	return nil
+}
+
+// TemplateDisplayNameValid returns whether the input string is a valid template display name.
+func TemplateDisplayNameValid(str string) error {
+	if len(str) == 0 {
+		return nil // empty display_name is correct
+	}
+	if len(str) > 64 {
+		return xerrors.New("must be <= 64 characters")
+	}
+	matched := templateDisplayName.MatchString(str)
+	if !matched {
+		return xerrors.New("must be alphanumeric with spaces")
+	}
+	return nil
+}