[Job] disables some formelements when job get activated

(#5624)

Intention
---------

when a job is activated this is like signing a contract,
all changes are now subject of further negotiations.
For now we just implement a formal start of the contract point.
[Job] disables some formelements when job get activated, adds appovalpage

(#5624) (#5634)

Intention
---------

when a job is activated this is like signing a contract,
all changes are now subject of further negotiations.
For now we just implement a formal start of the contract point.
Merge branch 'feature/job_approval_page' into develop