[FEATURE] Add verbose option to iGenVar

[Irallia]

We should discuss, if we want a verbose option. There are some commented out prints that you might want to use here.

There are already tests that can test this: #19

EDIT (29.03.2021):
To discuss:
In SeqAn3 we only have -hh as an exception, it's the only one. Every others are short ids and shuld throw if we use more.
Idea: new option -v, --verbose, which then takes an uint8_t for the verbose levels and has a default of 0.

EDIT (12.04.2021): We want to use the seqan verbose option from the argument parser

• _ spare
• -v 1 (Level 1): print ERROR <- default
• -v 2(Level 2): print WARNING, ERROR
• -v 3 (Level 3): print INFO, WARNING, ERROR