Allow input CSV file in SemApps importer

[fluidlog]

**Problem
For the moment, we can import only JSON files with SemApps Importer (via getAllFull).

Proposal
It would be great to allow CSV files too.

Alternatives
Two way to do that, make a specific importer for CSV file, or add a parameter to Importer mixin (ex : source.fileType).

[fluidlog]

Proposition of @srosset81 (in Archipelago matrix channel) :

You'd have to adapt the ImporterMixin, I'd say by adding a parameter like source.fileType and adapting the code here:

semapps/src/middleware/packages/importer/mixins/importer.js

Lines 330 to 358 in 8687009

	} else if (await isDir(param)) {
	// Parameter is a directory
	const filenames = await fsPromises.readdir(param);
	let files = [];
	for (const filename of filenames) {
	try {
	let content = await fsPromises.readFile(`${param}/${filename}`, { encoding: 'utf-8' });
	// Parse file if it is JSON
	try {
	content = JSON.parse(content);
	} catch (e) {
	// Ignore, we will provide the raw content
	}
	files.push(content);
	} catch (e) {
	this.logger.warn(`Could not read file ${param}/${filename}`);
	}
	}
	return files;
	} else {
	// Parameter is a file
	try {
	const file = await fsPromises.readFile(param);
	return JSON.parse(file.toString());
	} catch (e) {
	this.logger.warn(`Could not read file ${param}`);
	return false;
	}
	}

Note that in the case of folders, if you can't read a file, you pass the ‘raw’ contents. It would also be possible to do this for simple files

semapps/src/middleware/packages/importer/mixins/importer.js

Line 341 in 8687009

// Ignore, we will provide the raw content

... instead of returning an error

In this way the transform function would receive the contents of the CSV file, and could convert it