Java applet adaptions

[Stephan Bergmann]

With java.applet gone from Java 26 (<https://openjdk.org/jeps/504> "JEP 
504: Remove the Applet API"), I had to tweak 
<https://git.libreoffice.org/core/+/537057a44daa4a6e48bba21bf8655331041a09ac%5E%21> 
"external/beanshell: Adapt to java.applet gone from Java 26" and 
<https://git.libreoffice.org/core/+/5832a9db70344599de651471a3d807569ae2970f%5E%21> 
"external/hsqldb: Adapt to java.applet gone from Java 26" to keep them 
building.  I hope none of that broke any functionality that we would 
actually depend upon.

(And 
<https://wiki.documentfoundation.org/index.php?title=ReleaseNotes/26.8&oldid=868619> 
"removed OfficeBean SDK example", so that 
CustomTarget_odk/build-examples_java would not break.)