Badge with value 0 should use p-badge-no-gutter class

[mnhock]

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Current behavior
Badge component do not use p-badge-no-gutter class with values of length 1 in case of the value 0.

Expected behavior
Badge component should use p-badge-no-gutter class for value 0 as well.

This is the code which is not correct for the value 0:

'p-badge-no-gutter': this.value && String(this.value).length === 1,

should be:

'p-badge-no-gutter': this.value !== undefined && String(this.value).length === 1,

Reproduce:

    const value = 0;
    const value1 = 1;
    const value2 = 2;

    console.log(value && String(value).length === 1);   // 0  -> not correct should be true
    console.log(value1 && String(value1).length === 1); // true,
    console.log(value2 && String(value2).length === 1); // true