Fix issue 10562 dont flatten arrays to 1D when

[benjones]

RHS is an array

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	10562	normal	Cannot initialize arrays by an element value when the elements are fixed-length arrays

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub fetch digger
dub run digger -- build "master + dmd#10600"

[MoonlightSentinel]

This introduced a regression https://issues.dlang.org/show_bug.cgi?id=20465.
Fix: #10698