Allow query outputs to refer to a `FieldRef`. #1566

Job	Run time
Check lint and rustfmt	34s
Check fuzz targets	13s
Run JS linters	45s
Check rustdoc WASM target	31s
Run tests	1m 3s
WASM tests	1m 1s
Python tests and maturin build (3.9)	56s
pre-publish checks	0s
Python tests and maturin build (3.10)	45s
Python tests and maturin build (3.11)	41s
Python tests and maturin build (3.12)	1m 5s
All CI stages	1s
pre-publish checks	0s
publish trustfall_filetests_macros	0s
publish trustfall_core	0s
publish python trustfall	0s
publish trustfall_derive	0s
publish trustfall	0s
publish trustfall_stubgen	0s
	7m 35s

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