analyzer: fix ICE on COMPONENT_REF of ARRAY_TYPE [PR 93778]

PR analyzer/93778 reports an ICE with -fanalyzer on a gfortran test case
at this gimple stmt:

  _gfortran_st_set_nml_var (&dt_parm.0, &ro.xi.jq, &"ro%xi%jq"[1]{lb: 1 sz: 1}, 4, 0, D.3913);

where ro.xi.jq is a COMPONENT_REF, but ro.xi is of type "struct bl[3]".

The analyzer's handling of COMPONENT_REF assumes that the type of the
1st argument is a RECORD_TYPE or UNION_TYPE, whereas in this case it's
an ARRAY_TYPE, leading to a failed as_a inside
region_model::get_field_region.

This patch fixes the ICE by generalizing the "give up on this tree code"
logic from r10-6667-gf76a88ebf089871dcce215aa0cb1956ccc060895 for
PR analyzer/93388, so that the analyzer gives up when it needs to get an
lvalue for a COMPONENT_REF on something other than a RECORD_TYPE or
UNION_TYPE.

gcc/analyzer/ChangeLog:
	PR analyzer/93778
	* engine.cc (impl_region_model_context::on_unknown_tree_code):
	Rename to...
	(impl_region_model_context::on_unexpected_tree_code): ...this and
	convert first argument from path_var to tree.
	(exploded_node::on_stmt): Pass ctxt to purge_for_unknown_fncall.
	* exploded-graph.h (region_model_context::on_unknown_tree_code):
	Rename to...
	(region_model_context::on_unexpected_tree_code): ...this and
	convert first argument from path_var to tree.
	* program-state.cc (sm_state_map::purge_for_unknown_fncall): Add
	ctxt param and pass on to calls to get_rvalue.
	* program-state.h (sm_state_map::purge_for_unknown_fncall): Add
	ctxt param.
	* region-model.cc (region_model::handle_unrecognized_call): Pass
	ctxt on to call to get_rvalue.
	(region_model::get_lvalue_1): Move body of default case to
	region_model::make_region_for_unexpected_tree_code and call it.
	Within COMPONENT_REF case, reject attempts to handle types other
	than RECORD_TYPE and UNION_TYPE.
	(region_model::make_region_for_unexpected_tree_code): New
	function, based on default case of region_model::get_lvalue_1.
	* region-model.h
	(region_model::make_region_for_unexpected_tree_code): New decl.
	(region_model::on_unknown_tree_code): Rename to...
	(region_model::on_unexpected_tree_code): ...this and convert first
	argument from path_var to tree.
	(class test_region_model_context): Update vfunc implementation for
	above change.

gcc/testsuite/ChangeLog:
	PR analyzer/93778
	* gfortran.dg/analyzer/pr93778.f90: New test.