Summary
-------

Add 4 SHA-3 based new XML signature method URIs.

Problem
-------

Apache Santuario 3.0.3 introduced 4 new signature methods. We should add these as static final strings in the `SignatureMethod` class.

Solution
--------

Add the new signature method URIs.

Specification
-------------

Add these fields into `javax.xml.crypto.dsig.SignatureMethod`:

    /**
     * The <a href="http://www.w3.org/2007/05/xmldsig-more#sha3-224-rsa-MGF1">
     * SHA3-224-RSA-MGF1</a> (PKCS #1) signature method algorithm URI.
     *
     * @since 22
     */
    String SHA3_224_RSA_MGF1 =
            "http://www.w3.org/2007/05/xmldsig-more#sha3-224-rsa-MGF1";

    /**
     * The <a href="http://www.w3.org/2007/05/xmldsig-more#sha3-256-rsa-MGF1">
     * SHA3-256-RSA-MGF1</a> (PKCS #1) signature method algorithm URI.
     *
     * @since 22
     */
    String SHA3_256_RSA_MGF1 =
            "http://www.w3.org/2007/05/xmldsig-more#sha3-256-rsa-MGF1";

    /**
     * The <a href="http://www.w3.org/2007/05/xmldsig-more#sha3-384-rsa-MGF1">
     * SHA3-384-RSA-MGF1</a> (PKCS #1) signature method algorithm URI.
     *
     * @since 22
     */
    String SHA3_384_RSA_MGF1 =
            "http://www.w3.org/2007/05/xmldsig-more#sha3-384-rsa-MGF1";

    /**
     * The <a href="http://www.w3.org/2007/05/xmldsig-more#sha3-512-rsa-MGF1">
     * SHA3-512-RSA-MGF1</a> (PKCS #1) signature method algorithm URI.
     *
     * @since 22
     */
    String SHA3_512_RSA_MGF1 =
            "http://www.w3.org/2007/05/xmldsig-more#sha3-512-rsa-MGF1";