Autocomplete share "onOptionClick" for multiple instances

[bugy]

Bug description

If you add multiple autocomplete components on a page, their "onOptionClick" handlers are somehow interdependent
Here is an example (I just select options from 3 autocomplete in a row):

Codewise: in autocomplete.js there is the following code:

      let dropdownOptions = $.extend(
        Autocomplete.defaults.dropdownOptions,
        this.options.dropdownOptions
      );

So on every init we extend default options with new dropdown options. I.e. we modify defaults every time we create a new autocomplete.

This was introduced in #60

Steps to Reproduce

Create 3 autocomplete, like this:

      <div class="input-field">
        <input id="autocomplete-input" class="autocomplete" type="text">
        <label for="autocomplete-input">Autocomplete</label>
      </div>

      <div class="input-field">
        <input id="autocomplete-input2" class="autocomplete" type="text">
        <label for="autocomplete-input2">Autocomplete 2</label>
      </div>

      <div class="input-field">
        <input id="autocomplete-input3" class="autocomplete" type="text">
        <label for="autocomplete-input3">Autocomplete 3</label>
      </div>

And then initialize them:

    const autocompletes = document.querySelectorAll('.autocomplete');
    M.Autocomplete.init(autocompletes, {
      data: {
        'Apples': null,
        'Oranges': null,
        'Bananas': null
      }, minLength: 0
    });

Then just select options in each autocomplete one by one

As a result, you will see the behavior from the GIF above