Remove FUNCFLAG.compileTimeOnly

[RazvanN7]

Because it is redundant with FUNCFLAG.skipCodegen and used instead of SCOPE.compile.

As detailed in #14846 , the addition of compileTimeOnly was a hack to mask another hack.

#14846 untied the original hack so we can now tidy up the mess.

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Testing this PR locally

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[dkorpel]

Just needs to update the headers

[dkorpel]

They should also be removed from declaration.h:639

    bool isCompileTimeOnly() const;
    bool isCompileTimeOnly(bool v);

[RazvanN7]

@dkorpel ready, thanks!