write: add `LineConvert` #530

Job	Run time
bench	1m 18s
Build fuzz targets	1m 8s
coverage	1m 1s
build (ubuntu-latest, stable)	42s
build (ubuntu-latest, beta)	50s
cross (i686-unknown-linux-gnu)	42s
build (ubuntu-latest, nightly)	44s
doc	25s
cross (powerpc64-unknown-linux-gnu)	54s
features	3m 7s
build (stable, macOS-latest)	41s
msrv	2m 41s
rustfmt	4s
msrv-read	2m 41s
Run `debug_abbrev` fuzz target	5m 6s
Run `debug_aranges` fuzz target	5m 9s
Run `debug_info` fuzz target	5m 11s
Run `debug_line` fuzz target	5m 6s
Run `eh_frame` fuzz target	5m 5s
Run `eh_frame_hdr` fuzz target	5m 8s
	47m 43s

Provide feedback