Add QUARTER and DAY_OF_YEAR date functions with tests and docs

[Alperenu0]

What is the purpose of the change

This PR implements the missing date functions QUARTER and DAY_OF_YEAR for time-based analytics, as requested in the issue.

Fixes #791

Brief change log

• Added Quarter.java and DayOfYear.java in udf/table/date/ using the existing Joda-Time date-parsing approach (WeekOfYear.java as a template).
• Registered the new functions in BuildInSqlFunctionTable.java.
• Added comprehensive unit tests covering:
  • Leap year scenarios (e.g., Feb 29 and Dec 31 in a leap year).
  • Start/end-of-year boundaries (Jan 1 and Dec 31).
  • Null input handling.
• Updated the markdown documentation (date.md) with syntax, descriptions, and examples for both functions.

Verifying this change

This change added tests and can be verified as follows:

• DateTimeUtilTest / DateFunctionTest or related test suites run successfully.
• Manual verification via provided unit tests for boundary checks and leap years passed locally.

Does this PR introduce a breaking change?

• Yes
• No

[Copilot]

Pull request overview

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Implements missing date UDFs QUARTER and DAY_OF_YEAR and wires them into the DSL so they’re available for time-based analytics, with accompanying documentation updates.

Changes:

• Registers Quarter and DayOfYear UDFs in the built-in SQL function table.
• Updates date function documentation to include quarter and day_of_year.
• Updates test suite imports in preparation for new unit tests.

Reviewed changes

Copilot reviewed 3 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
geaflow/geaflow-dsl/geaflow-dsl-plan/src/test/java/org/apache/geaflow/dsl/udf/date/UDFDateTest.java	Adds imports for new date UDFs to support new/updated tests.
geaflow/geaflow-dsl/geaflow-dsl-plan/src/main/java/org/apache/geaflow/dsl/udf/table/date/WeekOfYear.java	Contains a whitespace-only header change that adds diff noise.
geaflow/geaflow-dsl/geaflow-dsl-plan/src/main/java/org/apache/geaflow/dsl/udf/table/date/DayOfYear.java	Contains a whitespace-only header change that adds diff noise.
geaflow/geaflow-dsl/geaflow-dsl-plan/src/main/java/org/apache/geaflow/dsl/schema/function/BuildInSqlFunctionTable.java	Registers the new Quarter and DayOfYear UDFs in the built-in SQL function table.
docs/docs-en/source/5.application-development/2.dsl/3.build-in/date.md	Documents syntax, description, and examples for quarter and day_of_year.

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