Snuba-sdk

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- Add a parent_api flag that is used to track the name of the calling API

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- Fix a bug in legacy converter that correctly handles infix conditions inside other functions

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- Add an AliasedExpression class that is used if the expression is in the select or groupby, which allows an alias of the results returned from Snuba. The alias is not used in any other clauses and is not available in the generated query in Snuba.
- Fix ALIAS_RE to allow single letter aliases
- Allow datetimes in legacy function strings (add : and - to allowed character list)

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- Allow square brackets in aliases

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- Try to convert wrapped conditions on tags to always use string comparisons.

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- Remove brittle, inconsistent and incomplete group by checks.