maven: Add support for md5 checkums to check download integrity
Some maven artifacts do not have any sha1 sums computed but rather md5 ones so handle these edge cases to still check download integrity of jar files.
See https://repo1.maven.org/maven2/org/jetbrains/kotlin/kotlin-test-annotations-common/1.5.30-M1/ for instance.
Depends on !347 (closed)
Fixes SWH-LOADER-CORE-1BP.
Migrated from D8840 (view on Phabricator)