Fix formatting of multiline variable declaration initializers

[srolel]

Fixes #19167

Sets the effectiveParentStartLine to the last line of a multiline variable declaration name, so that effectiveParentStartLine === startLine evaluates to true.

This fixes the case presented in the issue, and also for array destructuring. It does not handle the case of a type definition after the variable name:

const {
    a,
    b
}: {
    a: number,
    b: number
};

Or a type definition followed by an initializer:

const {
    a,
    b
}: {
    a: number,
    b: number
} = {
    a: 5,
    b: 4
};

Which will behave the same as prior to the fix. These can be fixed by offsetting effectiveParentStartLine to be the last line of the previous relevant Node, which I can do if the general idea is sound.

[typescript-bot]

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