extend autocast feature to control each attribute

[AlvaroVega]

autocast feature is performed by

iotagent-node-lib/lib/services/ngsi/ngsiUtils.js

Lines 98 to 134 in 9557e75

	function castJsonNativeAttributes(payload) {
	if (!config.getConfig().autocast) {
	return payload;
	}
	for (const key in payload) {
	if (
	/* eslint-disable-next-line no-prototype-builtins */
	payload.hasOwnProperty(key) &&
	payload[key].value &&
	payload[key].type &&
	typeof payload[key].value === 'string'
	) {
	if (payload[key].type === 'Number' && isFloat(payload[key].value)) {
	payload[key].value = Number.parseFloat(payload[key].value);
	} else if (payload[key].type === 'Number' && Number.parseInt(payload[key].value)) {
	payload[key].value = Number.parseInt(payload[key].value);
	} else if (payload[key].type === 'Boolean') {
	payload[key].value = payload[key].value === 'true' || payload[key].value === '1';
	} else if (payload[key].type === 'None') {
	payload[key].value = null;
	} else if (payload[key].type === 'Array' || payload[key].type === 'Object') {
	try {
	const parsedValue = JSON.parse(payload[key].value);
	payload[key].value = parsedValue;
	} catch (e) {
	logger.error(
	context,
	'Bad attribute value type. Expecting JSON Array or JSON Object. Received:%s',
	payload[key].value
	);
	}
	}
	}
	}
	return payload;
	}

It was introduced by dcalvoalonso#7 in 2.7.0 release of iota-node-lib

Currently is performing casting based on some attribute types (Boolean, Number, None) which is not the best.
But instead of that (which is not a best approach) control cast per attribute is proposed:

    {
        "name": "myNumber",
        "type": "MyCustomType",
        "autocastType": "Number",
        "autocast" : true
    }

as was suggested in #1020 (comment)

(autocast feature is used by iotagent-ul, but not used by iotagent-json)

[fgalan]

As follow up of this issue, the current autocast feature in IOTA-UL (IOTA_AUTOCAST env var and associated config.js setting) should be removed. It makes no sense to keep both system at the same time, it can be confusing for users.

[Sunny-NEC]

@AlvaroVega I am interested to work in this issue.
As per my understanding , In castJsonNativeAttributes casting take place on the basis of type.
and we have to extend the castJsonNativeAttributes or do casting on the basis of ( name, autocastType) attribute too.
Please confirm.

[AlvaroVega]

autocast should be done in base of proposed "autocastType" field and "autocast" flag of each attribute, possible in castJsonNativeAttributes or in another new function

[fgalan]

@Sunny-NEC thanks for your willingness to work on this issue! Please go ahead and create the pull request with your contribution, so we can evaluate and provide feedback.