Added VersionTLS constants and VersionName(version uint16) method

[mohrobati]

• Closes VersionTLS constants and VersionName(version uint16) are missing #4717
• Copied the following code from big go to add to src/crypto/tls/common.go

const (
	VersionTLS10 = 0x0301
	VersionTLS11 = 0x0302
	VersionTLS12 = 0x0303
	VersionTLS13 = 0x0304

	// Deprecated: SSLv3 is cryptographically broken, and is no longer
	// supported by this package. See golang.org/issue/32716.
	VersionSSL30 = 0x0300
)

// VersionName returns the name for the provided TLS version number
// (e.g. "TLS 1.3"), or a fallback representation of the value if the
// version is not implemented by this package.
func VersionName(version uint16) string {
	switch version {
	case VersionSSL30:
		return "SSLv3"
	case VersionTLS10:
		return "TLS 1.0"
	case VersionTLS11:
		return "TLS 1.1"
	case VersionTLS12:
		return "TLS 1.2"
	case VersionTLS13:
		return "TLS 1.3"
	default:
		return fmt.Sprintf("0x%04X", version)
	}
}

[deadprogram]

@mohrobati could you please rebase this PR against the latest `dev`` branch so as to resolve the unrelated build failure. Thank you!

[mohrobati]

@mohrobati could you please rebase this PR against the latest `dev`` branch so as to resolve the unrelated build failure. Thank you!

Done, thanks!

[deadprogram]

Thanks @mohrobati now merging.