Support EF.Constant for Cosmos

[cincuranet]

Related to #33674 and #34297.

[roji]

Note: the main reason to use EF.Constant is performance, i.e. for cases where a constant produces a more efficient query than a parameter (or in some cases, where integrating a parameter triggers EF bugs, e.g. around parameterized collations and type inference/collation). We are well aware of such cases in relational, but as of now I don't think we're aware of similar cases in Cosmos (though our knowledge of Cosmos query planning is generally not as advanced).

So putting this on the backlog for now, for us to gather feedback/investigate cases where EF.Constant would actually be useful on Cosmos.