Pass SAMPLEFORMAT to libtiff

[radarhere]

Resolves #5843

SAMPLEFORMAT is currently in the blocklist when saving with libtiff.

Pillow/src/PIL/TiffImagePlugin.py

Lines 1687 to 1689 in ae7c2cb

	blocklist += [
	REFERENCEBLACKWHITE,
	SAMPLEFORMAT,

The explanation is

Pillow/src/PIL/TiffImagePlugin.py

Lines 1679 to 1680 in ae7c2cb

	# SAMPLEFORMAT is determined by the image format and should not be copied
	# from legacy_ifd.

But SAMPLEFORMAT doesn't only come from the user. It can also be set by TiffImagePlugin, according to the image format.

Pillow/src/PIL/TiffImagePlugin.py

Lines 1477 to 1488 in ae7c2cb

	SAVE_INFO = {
	# mode => rawmode, byteorder, photometrics,
	# sampleformat, bitspersample, extra
	"1": ("1", II, 1, 1, (1,), None),
	"L": ("L", II, 1, 1, (8,), None),
	"LA": ("LA", II, 1, 1, (8, 8), 2),
	"P": ("P", II, 3, 1, (8,), None),
	"PA": ("PA", II, 3, 1, (8, 8), 2),
	"I": ("I;32S", II, 1, 2, (32,), None),
	"I;16": ("I;16", II, 1, 1, (16,), None),
	"I;16S": ("I;16S", II, 1, 2, (16,), None),
	"F": ("F;32F", II, 1, 3, (32,), None),

Pillow/src/PIL/TiffImagePlugin.py

Lines 1603 to 1604 in ae7c2cb

	if format != 1:
	ifd[SAMPLEFORMAT] = format

So this PR removes SAMPLEFORMAT from blocklist, allowing the value to be passed to libtiff by TiffImagePlugin's code - but also adding other code to still not allow the user to set it.