Gantt state docs (#1090)

* docs(gantt):state draft docs

* docs(gantt):set options through state examples

* docs(gantt): override user action and get column states examples

* docs(gantt):fix and polish examples

* docs(gantt):state docs

* Update _contentTemplates/gantt/state.md

Co-authored-by: Dimo Dimov <[email protected]>

* Update _contentTemplates/gantt/state.md

Co-authored-by: Dimo Dimov <[email protected]>

* Update _contentTemplates/gantt/state.md

Co-authored-by: Dimo Dimov <[email protected]>

* Update components/gantt/state.md

Co-authored-by: Dimo Dimov <[email protected]>

* Update components/gantt/state.md

Co-authored-by: Dimo Dimov <[email protected]>

* Update components/gantt/state.md

Co-authored-by: Dimo Dimov <[email protected]>

* Update components/gantt/state.md

Co-authored-by: Dimo Dimov <[email protected]>

* Update components/gantt/state.md

Co-authored-by: Dimo Dimov <[email protected]>

* Update components/gantt/state.md

Co-authored-by: Dimo Dimov <[email protected]>

* Update components/gantt/state.md

Co-authored-by: Dimo Dimov <[email protected]>

* Update components/gantt/state.md

Co-authored-by: Dimo Dimov <[email protected]>

* Update _contentTemplates/gantt/state.md

Co-authored-by: Dimo Dimov <[email protected]>

* docs(gantt): Revamp code style in template examples

* docs(gantt): Revamp code style in template examples 2

* docs(gantt): Revamp column state example code style

* docs(gantt): Revamp programmatic editing example

* docs(gantt):revamp samples

* docs(gantt):final touches

Co-authored-by: Dimo Dimov <[email protected]>

Author: ntacheva