Collect function

[anderson-joyle]

This is a rebased version of #2122, with all comments addressed.

[LucGenetier]

✅ No public API change. #Resolved

[LucGenetier]

✅ No public API change. #Resolved

[LucGenetier]

✅ No public API change. #Resolved

[LucGenetier]

✅ No public API change. #Resolved

[LucGenetier]

✅ No public API change. #Resolved

[LucGenetier]

✅ No public API change. #Resolved

[LucGenetier]

✅ No public API change. #Resolved

[LucGenetier]

✅ No public API change. #Resolved

[LucGenetier]

✅ No public API change. #Resolved

[LucGenetier]

✅ No public API change. #Resolved

[LucGenetier]

✅ No public API change. #Resolved

[LucGenetier]

✅ No public API change. #Resolved

[LucGenetier]

✅ No public API change. #Resolved

[CarlosFigueiraMSFT]

        var engine = new Engine(new PowerFxConfig(isPFxV1 ? Features.PowerFxV1 : Features.None));

Do we need this?

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Refers to: src/tests/Microsoft.PowerFx.Core.Tests.Shared/TexlTests.cs:147 in cb757a3. [](commit_id = cb757a3, deletion_comment = False)

[CarlosFigueiraMSFT]

        engine.Config.SymbolTable.AddFunction(new PatchAggregateSingleTableFunction());

[minor] can we just call EnableMutationFunctions instead of adding each function individually? If we don't call those, then we don't need the Patch functions either.

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Refers to: src/tests/Microsoft.PowerFx.Core.Tests.Shared/TexlTests.cs:158 in cb757a3. [](commit_id = cb757a3, deletion_comment = False)