[Feature] Add support for plantUML mindmap, wbs, gantt

[MSSandroid]

Copy of falsely closed pull request #3010

Description

I have added supprt for mindmap, wbs and gantt charts in plantuml. I just copied the part for the part for Ditaa chart and change the @ indicators and switched to svg output.
I havent added any tests, since I am not shure how. Test and lint have same output as current master

Issue fixed

Type of changes

• ⚪ Bug fix (Change that fixed an issue)
• ⚪ Breaking change (Change that can cause existing functionality to change)
• ⚪ Improvement (Change that improves the code. Maybe performance or development improvement)
• ✅ Feature (Change that adds new functionality)
• ⚪ Documentation change (Change that modifies documentation. Maybe typo fixes)

Checklist:

• ✅ My code follows the project code style
• ⚪ I have written test for my code and it has been tested
• ✅ All existing tests have been passed
• ✅ I have attached a screenshot/video to visualize my change if possible

[ZeroX-DG]

Instead of using require for every type of map, can we just require once and use it here?

const plantuml = require('markdown-it-plantuml');
this.md.use(plantuml, {...})
this.md.use(plantuml, {...})
this.md.use(plantuml, {...})

[ZeroX-DG]

Please edit your code and I'll approve right after this 😃

[ZeroX-DG]

Please share this stripTrailingSlash function instead of recreating it every time.

[ZeroX-DG]

LGTM 🎉