google-sheets connector: make Add charts step configurable from step definiton form

(Migrated from https://github.com/syndesisio/syndesis/issues/4564)

Author: *Matej Melko *
Assignees: Christoph Deppisch,

This is a...

[pre][code]
[x ] Feature request
[ ] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report [!-- Please search GitHub for a similar issue or PR before submitting --]
[ ] Documentation issue or request
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Description

Basicaly same as #4500. When we want to add chart in spreadsheet datamapper has to be always involved, which make some scenarios more complicated as it could be (i.e periodic chart update based on timer)