Uses only unpure-pure containers to articulate unpure-pure relationships (issue 3199)

Uses only unpure-pure containers to articulate unpure-pure relationships (issue 3199)

Previously, LilyPond used several different lists in define-grobs.scm
to define relationships between unpure and pure functions.  This patch
eliminates these lists, using unpure-pure containers to articulate
these relationships.

The modifications required to implement this change are described below:

-) axis-group-interface.cc
A Scheme function is no longer needed to determine pure relevant grobs.
All grobs can have their Y-extents meaningfully pure-evaluated now. The
worst-case scenario is that they evaluate to false. Dead grobs, on the
other hand, are never pure relevant. The calls to is_live are the only
holdovers from the old pure-relevant? scheme function.

-) grob-closure.cc
We allow unpure-pure containers in simple closures.

-) grob-property.cc
call_pure_function no longer looks up a Scheme module. Because there are
no hard-coded lists in Scheme any more, the function is smaller and
writing it in C++ gets slight efficiency gains.

-) grob.cc
pure_stencil_height used to be a Scheme function in define-grobs.scm.
Because it is much simpler (it no longer makes references to lists defined
in Scheme), it can be implemented in C++.

-) pure-from-neighbor-engraver.cc
Similar to axis-group-interface.cc, the pure-relevant distinction is
no longer important.

-) side-position-interface.cc
In order to avoid issues with alterBroken, we only check pure properties
before line breaking.

-) simple-closure.cc
Simple closures were incorrectly evaluated when containing unpure-pure
containers. This rectifies that.

-) stencil-integral.cc
Several pure equivalent functions needed to be written for skylines.

-) define-grobs.scm
Multiple overrides must be changed to unpure-pure containers. Previous
hard-coded lists are all deleted and several functions moved to C++ (see
above).

-) output-lib.scm
Several common unpure-pure containers used in define-grobs.scm are
defined here. Several functions from define-grobs.scm pertaining to
grob offsets are moved to this file.