Add support for modVal : '*' in declMod

[tadatuta]

Used for example in https://github.com/bem/bem-components/blob/v3/common.blocks/button/_togglable/button_togglable.js#L12 or https://github.com/bem/bem-components/blob/v3/common.blocks/popup/_target/popup_target.js#L31

modules.define('b1', ['i-bem-dom'], function(provide, bemDom) {

provide(bemDom.declBlock(this.name, {
    m1: function() {
        console.log('initial m1');
    },
    m1_v1: function() {
        console.log('initial m1_v1');
    }
}));

});

modules.define('b1', function(provide, B1) {

provide(B1.declMod({ modName: 'm1' }, {
    m1: function() {
        console.log('overriden m1');
    }
}));

});

modules.define('b1', function(provide, B1) {

provide(B1.declMod({ modName: 'm1', modVal: 'v1' }, {
    onSetMod: {
        js: {
            inited: function() {
                this.m1();
                this.m1_v1();
            }
        }
    },
    m1_v1: function() {
        console.log('overriden m1_v1');
    }
}));

});

Expected: overriden m1 overriden m1_v1.
Actual result: initial m1 overriden m1_v1.

[veged]

we change semantic of omitted modVal accordingly to setMod (if no modVal it's short cut for modVal : true)

so we need to add support for B1.declMod({ modName: 'm1', modVal: '*' }, as in onSetMod