RFR: 8264019: Use the blessed modifier order in java.xml

[Alex Blewitt]

As a subtask of JDK-8263854 this cleans up the `java.xml` module to used the blessed modifier order.

-------------

Commit messages:
 - Reordered final static to static final
 - Use the blessed modifier order in java.xml

Changes: https://git.openjdk.java.net/jdk/pull/3091/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3091&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8264019
  Stats: 336 lines in 85 files changed: 0 ins; 0 del; 336 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3091.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3091/head:pull/3091

PR: https://git.openjdk.java.net/jdk/pull/3091