## What changes were proposed in this pull request?
#19201 introduced the following regression: given something like `df.withColumn("c", lit(2))`, we're no longer picking up `c === 2` as a constraint and infer filters from it when joins are involved, which may lead to noticeable performance degradation.
This patch re-enables this optimization by picking up Aliases of Literals in Projection lists as constraints and making sure they're not treated as aliased columns.
## How was this patch tested?
Unit test was added.
Author: Adrian Ionescu <adrian@databricks.com>
Closes#20155 from adrian-ionescu/constant_constraints.
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