srm: generate SRM v2.2 Axis-generated code as part of build process

Previously, SRM v2.2 code was generated by Axis v1.3 and committed
to VCS.  After this, some changes were made to the code, mostly
superficial.  Specifically:

  o  axis-generated single-line if-statements were changed to dCache
     style (commit 38841d52)

  o  the Serializable classes had their serialVersionUID added
     explicitly (commit d09fa438)

  o  Axis-generated redundant field-member initialisers were
     removed (commit 3e4d9b29)

  o  The TStatusCode class had an isProcessing method added
     (commit 0cd9d2d1)

This patch removes the auto-generated code and uses a maven plugin
to generate the code as part of the maven build process.  A patch
introduces the isProcessing method, but all other changes above are
lost.

Target: master
Requires-book: no
Requires-notes: no
Patch: https://rb.dcache.org/r/7186/
Acked-by: Gerd Behrmann