Add "timezone_region" and "timezone_abbr" support for EXTRACT (and DATE_PART)

[alexander-beedie]

Adds "timezone_region" and "timezone_abbr"¹ as recognised DateTimeField values.

EXTRACT(timezone_abbr FROM "dt")
EXTRACT(timezone_region FROM "dt")

Footnotes

1. Oracle: EXTRACT docs ↩

[coveralls]

Pull Request Test Coverage Report for Build 7527965721

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.003%) to 87.858%

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Totals
Change from base Build 7527748620:	0.003%
Covered Lines:	18849
Relevant Lines:	21454

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💛 - Coveralls

[alamb]

Thank you for the contribution @alexander-beedie - the code and tests look good in this PR . I am not sure about the commented out test however.

[alexander-beedie]

Thank you for the contribution @alexander-beedie - the code and tests look good in this PR . I am not sure about the commented out test however.

Fixed; sorry about that one ;)

[alamb]

LGTM -- thanks again @alexander-beedie