Added RebarShape property to the Rebar object and defined setEdit() function in Rebar object

[amrit3701]

Thank you for creating a pull request to contribute to FreeCAD! To ease integration, please confirm the following:

• Branch rebased on latest master git pull --rebase upstream master
• Unit tests confirmed to pass by running ./bin/FreeCAD --run-test 0
• Commit message is well-written
• Commit message includes issue #<id> or fixes #<id> where <id> is the associated MantisBT issue id if one exists

And please remember to update the Wiki with the features added or changed once this PR once it is merged.

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Here is the discussion:
https://forum.freecadweb.org/viewtopic.php?f=8&t=22760&sid=79c51c31fe569e09e33dad7e90853c0b#p177059

[wwmayer]

@yorikvanhavre your turn :)

[yorikvanhavre]

merged