note         = {\url{http://www.arcway.com/fileadmin/arcwaydateien/pdf/BPRE_Whitepaper.pdf}, visited 2007-09-15},

should become

url = {http://www.arcway.com/fileadmin/arcwaydateien/pdf/BPRE_Whitepaper.pdf},
note = {visited 2007-09-15},

The conversion should be named "Move URLs in note field to url field".

Should be placed as third the upper part of the cleanup dialog: https://docs.jabref.org/finding-sorting-and-cleaning-entries/cleanupentries

One can look at jabRef/jabref/src/main/java/org/jabref/logic/cleanup/EprintCleanup.java for an impression, how the implementation should like. There is also a test case: jjabRef/jabref/src/test/java/org/jabref/logic/cleanup/EprintCleanupTest.java

Please use @ParameterizedTest if possible (and doing more than one test, which is recommended).