release 2.2.0

refactor: replace commons-codec with JDK Base64/HexFormat, drop gnu-c…

…rypto

Java 17 ships java.util.Base64 (since 8) and java.util.HexFormat (since 17),
so commons-codec is redundant. gnu-crypto was declared in pom.xml but never
imported.

increase version to 2.0.0 (major version increase for EBICS 3.0)

mark the slf4j-simple dependency as optional

increase version to 1.2