Add ImageEncoder implementation for Hdr (rebase of #2013) #1411

Job	Run time
build_benchmarks	42s
Fuzz targets (cargo-fuzz)	53s
Fuzz targets (afl)	1m 21s
cargo-deny	20s
clippy	2m 0s
public_private_dependencies	24s
rustfmt	4s
test_avif_decoding	1m 29s
test_features	38s
test_toolchains (1.67.1)	31s
test_other_archs (powerpc-unknown-linux-gnu)	1m 0s
test_toolchains (nightly)	37s
test_other_archs (i686-unknown-linux-gnu)	53s
test_toolchains (beta)	23s
test_features (default)	28s
test_features (rayon)	32s
test_features (avif)	1m 9s
test_features (bmp)	33s
test_features (dds)	28s
test_features (exr)	41s
test_features (ff)	28s
test_features (gif)	31s
test_features (hdr)	8s
test_features (ico)	37s
test_features (jpeg)	44s
test_features (png)	36s
test_features (pnm)	28s
test_features (qoi)	35s
test_features (tga)	43s
test_features (tiff)	41s
test_features (webp)	38s
	21m 15s

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