Add 2fa for authentification (#383)

Fix user tests

Add swagger docs

Fix lint

Add totp check when logging in

Make totp enrollment work

Add migration for totp table

go mod vendor

Add routes for totp routes

Add route handler for totp routes

Add basic implementation to enroll a user in totp

Co-authored-by: kolaente <k@knt.li>
Reviewed-on: https://kolaente.dev/vikunja/api/pulls/383

vendor/github.com/boombuler/barcode/utils/runeint.go

@@ -0,0 +1,19 @@
+package utils
+
+// RuneToInt converts a rune between '0' and '9' to an integer between 0 and 9
+// If the rune is outside of this range -1 is returned.
+func RuneToInt(r rune) int {
+	if r >= '0' && r <= '9' {
+		return int(r - '0')
+	}
+	return -1
+}
+
+// IntToRune converts a digit 0 - 9 to the rune '0' - '9'. If the given int is outside
+// of this range 'F' is returned!
+func IntToRune(i int) rune {
+	if i >= 0 && i <= 9 {
+		return rune(i + '0')
+	}
+	return 'F'
+}