Fix 'missing the Job/Configure permssion' error on Branch Sources page

[sacredheartsc]

Fix 'missing the Job/Configure permssion' error on Branch Sources page when used with the Role-Based Authorization Strategy plugin (JENKINS-72821)

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When this plugin is used in combination with the "Role-Based Authorization Strategy", the "Branch Sources" job configuration page throws the following error:

$USER is missing the Job/Configure permission

This error is shown even when the user has full Admin rights on the Jenkins instance.

I'm not sure that this fix is 100% correct, but it does resolve the problem. I noticed that another PR in a similar project fixed a similar issue (JENKINS-60116) by checking for the EXTENDED_READ permission.

So, I blindly did the same thing. Would appreciate someone checking my work!

Fixes #823