Enhancement: Add default ignore file to mode file

[alex-ip]

We need to specify an ignore file to filter the files that are read in. This ignore file is likely to vary with the RO-crate profile chosen, so we could specify it in the Crate-O mode file.

For example, we could associate the .gitignore file with the Software Source Code RO-Crate Profile in the mode file for this profile. This would be used to filter the file list when the user selects "Load Files". The ignore settings could be applied unconditionally at first, and we could consider allowing the user to override or disable the entries later.

We may also wish to ignore a standard selection of file globs (e.g. "." and "~") - we might want to read these from a configuration file.

Could we use a section in the mode file as follows?

	"ignore": {
		"ignoreFiles": [
			".gitignore"
		],
		"ignoreGlobs": [
			".*",
			"~*",
			"*.tmp"
		]
	}