Add `From<T>` conversions to `FieldValue` for usize and NonZero types. #1782

Job	Run time
Check lint and rustfmt	1m 17s
Check fuzz targets	16s
Run JS linters	51s
Check rustdoc WASM target	20s
Run tests	1m 7s
WASM tests	54s
Python tests and maturin build (3.9)	1m 11s
pre-publish checks	0s
Python tests and maturin build (3.10)	1m 11s
Python tests and maturin build (3.11)	1m 7s
Python tests and maturin build (3.12)	1m 7s
Python tests and maturin build (3.13)	1m 23s
All CI stages	1s
pre-publish checks	0s
publish trustfall_filetests_macros	0s
publish trustfall_core	0s
publish trustfall_derive	0s
publish python trustfall	0s
publish trustfall	0s
publish trustfall_stubgen	0s
	10m 45s

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