Added: Project plugin retrieve jsgantt module via npm (OFBIZ-12804)

An outdated version of jsgantt was previously included in
ofbiz-framework sources as part of common-theme. These sources have been
removed from common-theme and the project plugin will now retrieve an
updated version of jsgantt, jsgantt-improved, from NPM.

The newer version of jsgantt is not completely compatible with the
previous version used by OFBiz, so some changes in how the gantt chart
was initialised were necessary.

Common code has been extracted to static javascript file. Data
representing gantt chart items is rendered to a hidden field on screen
where it is retrieved by client-side code and used to construct the
gantt chart.
11 files changed