[LESS] Fixing issues with spacing when an object literal lives inside a mixin

[mhnaeem]

Description

Fix issues with spacing in LESS code when using object literals inside mixins. The changes in this PR could be considered breaking since but I believe they are correct.

Fixes Issue:

• LESS mixins gets formatted strangely #722
• LESS mixin unexpected code formatting #2016
• LESS mixin unexpected code formatting microsoft/vscode#146693

Fixes #722
Fixes #2016

[mhnaeem]

Had to change this test because I believe it is incorrect. It adds extra indents to properties which is unexpected, this test also conflicting with my fixes. I have added example of what it would look like before my changes and after.

Before PR:

@set: {
    one: blue;
    two: green;
    three: red;
}
.set {
    each(@set, {
            @{key}-@{index}: @value;
        }
    );
}

After PR:

@set: {
    one: blue;
    two: green;
    three: red;
}
.set {
    each(@set, {
        @{key}-@{index}: @value;
    });
}

[mhnaeem]

Please refer to the example on the LESS's website which also uses the same formatting as after my changes
https://lesscss.org/functions/#list-functions-each

[bitwiseman]

You are correct. Sometimes the tests document existing wrong behavior so that we'll know when something is fixed.

[bitwiseman]

Nicely done!