Drop support for returning non-UTF-8 encoded responses

[Fdawgs]

The /pdf/html and /pdf/txt routes both support the option to produce non-UTF-8 encoded results via the outputEncoding query string param:

docsmith/src/routes/pdf/html/schema.js

Lines 94 to 124 in 564cad8

	.prop(
	"outputEncoding",
	S.string()
	.default("UTF-8")
	.description("Sets the encoding to use for text output")
	// Encodings supported by Poppler
	.enum([
	"ASCII7",
	"Big5",
	"Big5ascii",
	"EUC-CN",
	"EUC-JP",
	"GBK",
	"ISO-2022-CN",
	"ISO-2022-JP",
	"ISO-2022-KR",
	"ISO-8859-6",
	"ISO-8859-7",
	"ISO-8859-8",
	"ISO-8859-9",
	"KOI8-R",
	"Latin1",
	"Latin2",
	"Shift-JIS",
	"TIS-620",
	"UTF-8",
	"UTF-16",
	"Windows-1255",
	"ZapfDingbats",
	])
	)

However, these are legacy encodings, W3C recommends using UTF-8 for everything, and the HTML standard reflects this.

These encodings are also not tested in this repo so cannot confirm the correctness of the output, and I have yet to encounter any use-case for them in any modern clinical setting.