HPCC-17982 DynamicESDL: Forms should indicate visible optional fields

[mayx]

• Change esxdl2xsd.xslt file to include the optional attribute in the
  generated xsd.
• Change gen_form.xsl to add value of the optional next to the field
  name in the generated html form.

Signed-off-by: mayx yanrui.ma@lexisnexisrisk.com

Type of change:

• This change is a bug fix (non-breaking change which fixes an issue).
• This change is a new feature (non-breaking change which adds functionality).
• This change is a breaking change (fix or feature that will cause existing behavior to change).
• This change alters the query API (existing queries will have to be recompiled)

Checklist:

• My code follows the code style of this project.
  • My code does not create any new warnings from compiler, build system, or lint.
• The commit message is properly formatted and free of typos.
  • The commit message title makes sense in a changelog, by itself.
  • The commit is signed.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly, or...
  • I have created a JIRA ticket to update the documentation.
  • Any new interfaces or exported functions are appropriately commented.
• I have read the CONTRIBUTORS document.
• The change has been fully tested:
  • I have added tests to cover my changes.
  • All new and existing tests passed.
  • I have checked that this change does not introduce memory leaks.
  • I have used Valgrind or similar tools to check for potential issues.
• I have given due consideration to all of the following potential concerns:
  • Scalability
  • Performance
  • Security
  • Thread-safety
  • Premature optimization
  • Existing deployed queries will not be broken
  • This change fixes the problem, not just the symptom
  • The target branch of this pull request is appropriate for such a change.
• There are no similar instances of the same problem that should be addressed
  • I have addressed them here
  • I have raised JIRA issues to address them separately
• This is a user interface / front-end modification
  • I have tested my changes in multiple modern browers
  • The component(s) render as expected

Testing:

[mayx]

@afishbeck Hi Tony please code review when you have a chance.

[HPCCSmoketest]

Automated Smoketest: ✅
Sha: 7e4ba39
Build: success
Build: success
ECL Watch: Rebuilding Site

errors	warnings	build time
0	65	94.558 seconds

Install hpccsystems-platform-community_6.4.0-rc6.el7.x86_64.rpm
HPCC Start: OK

Unit tests result:

Test	total	passed	failed	errors	timeout
unittest	95	95	0	0	0
wutoolTest(Dali)	19	19	0	0	0
wutoolTest(Cassandra)	19	19	0	0	0

Regression test result:

phase	total	pass	fail
setup (hthor)	11	11	0
setup (thor)	11	11	0
setup (roxie)	11	11	0
test (hthor)	733	733	0
test (thor)	627	627	0
test (roxie)	760	760	0

HPCC Stop: OK
HPCC Uninstall: OK

[afishbeck]

@mayx looks fine