feat: enhance error output on not valid name and label names

[ManuelLG92]

While working I was facing an error performing some testing because of no valid metric name and no valid label names.
I decided to dive into the code to get more output in the error.

The changes are the following:

• Show the invalid name in the error.

  • Original:
    Invalid metric name
  • Improvement:
    Invalid metric name: ${this.name}

• Show the invalid label names instead of a generic message

  • Change the check of every to filter by the regex, and return the invalid labels. So it returns an array instead of a boolean
  • Check if the array length is higher than 0, then the error is thrown.
    • Original:
      throw new Error('Invalid label name');
    • Improvement:
      Invalid metric name: ${this.name}

  The changes have been tested by unit testing inside the gauge test case. It could be in any other metric that inherits from the metric abstract class.