Add a way to add callbacks through references

[akaIDIOT]

Not really sure of the implementation, it's all very stringy and regexy, but the tests do look to be working fairly simply, while maintaining a simple to read something that would implement a way to insert secrets from a place that has nothing to do with confidence 😎

This would be an alternative to #111

[github-actions]

Comparing median (lower is better) metric of benchmarks between this PR's target (562ed1c) and the HEAD of this PR (74f1424):

	3.10	3.11	3.12	3.13	3.14	3.15	PyPy 3.10	PyPy 3.11
test_benchmark_get	+16%	+12%	+9%	+8%	+16%	+12%	+18%	-2%
test_benchmark_get_dotted	+2%	-1%	+0%	-2%	+1%	+1%	-0%	+4%
test_benchmark_getattr	+13%	+10%	+9%	+9%	+14%	+10%	+19%	+4%
test_benchmark_getitem	+15%	+9%	+10%	+9%	+14%	+13%	+19%	+0%
test_benchmark_getitem_dotted	+3%	+1%	-0%	-2%	+1%	+0%	-1%	+7%
test_benchmark_init_full_overlap	+0%	+0%	-0%	+0%	+3%	+1%	+0%	-1%
test_benchmark_init_no_overlap	-0%	+1%	+0%	+2%	-0%	+1%	+0%	-0%
test_benchmark_init_partial_overlap	-0%	+2%	+0%	+1%	+0%	+0%	+1%	-0%
test_benchmark_match_mapping	+11%	+9%	+6%	+6%	+10%	+8%	+11%	+2%
test_benchmark_reference_chain	+50%	+32%	+31%	+28%	+30%	+35%	+158%	+137%
test_benchmark_splat_args	-1%	+1%	-1%	-0%	+0%	+0%	-2%	-2%
test_benchmark_spread_kwargs	-3%	+1%	-3%	-3%	-2%	+0%	+2%	-2%

(This comment will be updated on subsequent pushes)