Implement propertyMissing method

[Willem1987]

Undo extending all Declarations from GenericPipelineDeclaration (this adds unwanted properties)
Remove GenericPipelineDeclaration implementation of getProperty.
Instead implement propertyMissing method to fallback to env and params.
Append test to use env var before pipeline closure
Remove duplicate method executeOn (use executeWith instead)
Remove name conflicts between JenkinsFile closures and Declaration fields

Our JenkinsFile had this:

def call() {
    String someValue = SomeHelper.someMap.get(ENV_VAR);

    pipeline {
    }
}

It seems the previous fix to handle looking into env. and params. does not work outside the pipeline closure. Therefore i looked for another way to fix this.
During this i noticed the effect extending GenericPipelineDeclaration has on the function printNonNullProperties of ObjectUtils.
So i undid the extending of PipelineDeclaration for declarations that should not be able to handle all those functions(agent, steps etc).

[stchar]

Have a question regarding reverting some changes

[stchar]

I think at the moment we create a new instance of whatever we should call our custom class loader.
the problem is createComponent method is static so I'm not sure how to retrieve it.

[stchar]

so no additional juggling with bindings are required in execute neither with componentInstance

[Willem1987]

I'm sorry i don't quite follow. Are you saying we want to get rid of the createComponent call alltogether? The only change i did in this MR is flip 2 vars around. Making closure the delegate and componentInstance the owner. So that the closure is evaluated before accessing the Declaration class methods/vars

[Willem1987]

@stchar I tried simplifying the whole class loading.

The idea:
We only need stack interception for Script calls? (not the declaration setup calls, as far as i understand it)
The declaration classes get called to set properties as a sort of setup of the stack. When execute is called on the Declaration it uses the Script to get the correct depth and stack logging to work.
The parameters declaration now uses the binding of the closure (coming from PipelineTestHelper/BasePipelineTest)

A problem i ran into when trying to intercept the declaration classes is calling super methods. More specifically the super.execute call in NotDeclaration. The current MethodInterceptor seems unable to distinguish when to call NotDeclaration.execute vs super(/WhenDeclaration).execute. It seems to keep trying to intercept and invoke NotDeclaration.execute. This caused when_not_branch_master to fail.

So from that i tried just making sure the closures get bound to a Declaration delegate and the Declaration class delegates calls throug the script to get through the Stack interception

[stchar]

I would prefer not to copy-paste same code in different classes inheritance here is a good practice

[Willem1987]

The stage should clear the environment/params after finishing so the next stage could inherit pipeline vars. But i guess we could implement the cleanup at GenericPipeline level

[Willem1987]

I created a public static method to init and reset the environment props. This way we can share the logic, but choose when to call the parts.

We want to init the env in a stage, but only reset it after the stage is complete. Super.execute would have immediately cleared the stage custom env overrides.