fix(refinements): allow Interp to refine none to everything

[math-fehr]

Currently, if the interpretation fails in either the source or the target program, there is no refinement relation between them.

With this PR, a failure in the source program interpretation implies that any target program refines the source.

[github-actions]

VeIR Benchmarks

Details

Benchmark suite	Current: 36fdcec	Previous: eb0390c	Ratio
add-fold-worklist/create	2168000 ns (± 102137)	2198000 ns (± 109413)	0.99
add-fold-worklist/rewrite	3741500 ns (± 74781)	3733000 ns (± 84672)	1.00
add-fold-worklist-local/create	2263000 ns (± 98754)	2191000 ns (± 99246)	1.03
add-fold-worklist-local/rewrite	3120000 ns (± 72053)	3011000 ns (± 27372)	1.04
add-zero-worklist/create	2138000 ns (± 70694)	2140500 ns (± 109777)	1.00
add-zero-worklist/rewrite	2379000 ns (± 41191)	2383000 ns (± 53970)	1.00
add-zero-reuse-worklist/create	1819500 ns (± 87706)	1798000 ns (± 63295)	1.01
add-zero-reuse-worklist/rewrite	1977000 ns (± 57977)	1965000 ns (± 30368)	1.01
mul-two-worklist/create	2200000 ns (± 45335)	2191000 ns (± 103104)	1.00
mul-two-worklist/rewrite	5250000 ns (± 67954)	5176000 ns (± 80037)	1.01
add-fold-forwards/create	2277000 ns (± 94603)	2174500 ns (± 97824)	1.05
add-fold-forwards/rewrite	2947000 ns (± 63131)	2967500 ns (± 35897)	0.99
add-zero-forwards/create	2200000 ns (± 45177)	2115000 ns (± 33441)	1.04
add-zero-forwards/rewrite	1929000 ns (± 60763)	1903000 ns (± 16300)	1.01
add-zero-reuse-forwards/create	1803000 ns (± 59743)	1832000 ns (± 91568)	0.98
add-zero-reuse-forwards/rewrite	1550000 ns (± 33404)	1555000 ns (± 50375)	1.00
mul-two-forwards/create	2170000 ns (± 104035)	2126000 ns (± 70864)	1.02
mul-two-forwards/rewrite	3714000 ns (± 158236)	3520000 ns (± 48872)	1.06
add-zero-reuse-first/create	1816000 ns (± 79226)	1827500 ns (± 94828)	0.99
add-zero-reuse-first/rewrite	8000 ns (± 1062)	8000 ns (± 1592)	1
add-zero-lots-of-reuse-first/create	1798000 ns (± 86483)	1773000 ns (± 69739)	1.01
add-zero-lots-of-reuse-first/rewrite	803000 ns (± 30210)	759000 ns (± 9407)	1.06

This comment was automatically generated by workflow using github-action-benchmark.

[tobiasgrosser]

Post-merge review, this is exactly what we want. It helps #774.