Query: Fixes c# query parser to handle Alias in from clause

[leminh98]

Pull Request Template

Description

This fixes the managed parser bug where it would throw error while parsing a valid aliased FROM clause without the AS keyword

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• [] New feature (non-breaking change which adds functionality)
• [] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [] This change requires a documentation update

Closing issues

closes #2568

[github-actions]

Please follow the required format: "[Internal] Category: (Adds|Fixes|Refactors|Removes) Description"

Internal should be used for PRs that have no customer impact. This flag is used to help generate the changelog to know which PRs should be included. Examples:
Diagnostics: Adds GetElapsedClientLatency to CosmosDiagnostics
PartitionKey: Fixes null reference when using default(PartitionKey)
[v4] Client Encryption: Refactors code to external project
[Internal] Query: Adds code generator for CosmosNumbers for easy additions in the future.

All good!

[sboshra]

select_item : scalar_expression (K_AS IDENTIFIER)? ;

please make this optional

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Refers to: Microsoft.Azure.Cosmos/src/Query/Core/Parser/sql.g4:22 in db2ff51. [](commit_id = db2ff51, deletion_comment = False)

[sboshra]