cd target/ before doing the code-signing

This is so that ./build.py clean will remove any logs or temporary directories
Disable jar-signing in update-version target
Remove Empty menu. (see #12157)
Merge pull request #2241 from manics/more_webstart_codesigning_tweaks

Run the code-signing script from the target dir
Merge pull request #2246 from jburel/view-menu

Remove Empty menu. (see #12157)
Update dev_5_0 submodules

Repository: openmicroscopy/openmicroscopy
Already up-to-date.

Repository: openmicroscopy/bioformats
Updating f336f17..b5a33fe
Merged PRs (fast-forward):
  # PR 1013 melissalinkert 'Update version numbers to 5.0.1'
  # PR 1023 melissalinkert 'Update version history for 5.0.1'
  # PR 1021 melissalinkert 'Minor docs autogen fixes'
  # PR 1022 ctrueden 'OME-XML package bug-fix'

Repository: ome/scripts
Already up-to-date.

Repository: openmicroscopy/ome-documentation
Updating 846e636..8005a1f
Merged PRs (fast-forward):
  # PR 719 joshmoore '5.0.1 upgrade additions.'
  # PR 717 aleksandra-tarkowska 'Session engine update'
  # PR 715 rleigh-dundee 'sysadmins: Merge installation sections'
  # PR 713 joshmoore 'In-place documentation'

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