[Formatter] Indent Right(hand side) `CommandExpressionAst`

Indent (a multiline) righthand side (list) expression assignment.
Meaning, for a (multiline) Statements.Right CommandExpressionAst (as apposed to Ast's that have already their own embedded indention, as e.g. a PipelineAst), I would like the righthand side to (optionally?) increase the indent:

Wrong way (?)

$List =
'One',
'Two',
'Three'

Correct way

$List =
    'One',
    'Two',
    'Three'

Wrong way (?)

$4 = # or any lengthy variable name aka dot notation
2 + 2

Correct way

$4 = # or any lengthy variable name aka dot notation
    2 + 2

未指定文件或测试；首先定位 formatter 对 CommandExpressionAst 的处理，并将其与此 issue 中的多行示例进行比较。当多行右侧列表或表达式赋值获得所要求的增加缩进，且不改变已经自行管理缩进的 AST 构造时，即视为完成。