Deprecate printToFile

[tresf]

Printing to file should be extremely restricted, like #306 and only allow writing to certain pre-approved locations.

qz.configs.create({ file: 'foo/bar.txt'});
// -- OR --
cfg.setPrinter({ file: 'foo/bar.txt'});

Considerations

• This technique is still somewhat popular for writing to a UNC path. e.g. \\print-server\printer-share\my printer. We should consider allowing non-loopback UNC paths. Detecting a non-loopback can be tricky. e.g. \\127.0.0.1\, \\COMPUTER\\, as well as IPv6 variants. This may make UNC too difficult to support. A decision must be made on UNC paths.
• Add a deprecation warning immediately for this feature, since it needs to be removed or inhibited. (Done via 80bd7ae)
• It may be viable to alias this to a convenience wrapper around FileIO writing. That way the existing FileIO whitelisting techniques can be reused.
• As a replacement to users using this feature, we'd may offer instructions for setting up a file-printer. This varies per-platform.

Use Cases

I believe existing deployments fall into the the following three use-cases.

• A shortcut to print raw to a UNC share
  • See consideration above about possibly keeping UNC path support
• Testing/troubleshooting raw content
  • This can be mitigated by adding instructions for setting up a RAW file printer
• 3rd-party device interfacing
  • Superseded by File communication interface #306

Some relevant code snippets:

tray/src/qz/printer/action/PrintRaw.java

Lines 286 to 288 in 572191a

	} else if (output.isSetFile()) {
	printToFile(output.getFile(), bab.getByteArray());
	} else {

tray/src/qz/printer/PrintOutput.java

Lines 33 to 42 in b3e3640

	if (configPrinter.has("file")) {
	String filename = configPrinter.getString("file");
	if (!FileUtilities.isGoodExtension(Paths.get(filename))) {
	throw new IllegalArgumentException("Writing to file \"" + filename + "\" is denied for security reasons. (Prohibited file extension)");
	} else if (FileUtilities.isBadPath(filename)) {
	throw new IllegalArgumentException("Writing to file \"" + filename + "\" is denied for security reasons. (Prohibited directory name)");
	} else {
	file = new File(filename);
	}
	}

Supersedes #631

[tresf]

Closed via #1213