assert correct URLs

[jkowalleck]

Similar to CycloneDX/cyclonedx-php-library#35
Similar to CycloneDX/cyclonedx-javascript-library#992

---

have all the XML strings that are anyURI somehow fixed before rendering the XML.
affected elements:

• component.purl
• license.url
• externalReterence.url
• and so on ...

according to XML spec the anyURI needs to conform to https://www.ietf.org/rfc/rfc2396.txt

 * @see http://www.w3.org/TR/xmlschema-2/#anyURI
 * @see http://www.datypic.com/sc/xsd/t-xsd_anyURI.html


    /* URIs require that some characters be escaped with their hexadecimal Unicode code point preceded by the %
     * character. This includes non-ASCII characters and some ASCII characters, namely control characters, spaces,
     * and the following characters (unless they are used as deliimiters in the URI): <>#%{}|\^`.
     * [...]
     * The only values that are not accepted are ones that make inappropriate use of reserved characters, such as ones that contain multiple # characters or have % characters that are not followed by two hexadecimal digits.
     * -- as of http://www.datypic.com/sc/xsd/t-xsd_anyURI.html
     */