docs: Update DAX API function reference

[MazterQyou]

Check List

• Tests have been run in packages where changes made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

Description of Changes Made

This PR updates DAX API function reference, specifically:

• Mark unsupported features as supported in AVERAGEA, MAX, MIN aggregation functions
• Mention that the value of COUNTROWS aggregation function now reports 50000 instead of 1
• Mark unsupported features as supported in DAY, HOUR, MINUTE, MONTH, QUARTER, SECOND, TIME, WEEKDAY, YEAR date and time functions
• Mention that time zone may depend on data warehouse settings in NOW, TODAY, UTCNOW, UTCTODAY date and time functions
• Add a new section for INFO functions
• Remove ISBLANK information function caveat
• Mark unsupported feature as supported in IF logical function
• Mention that IF function coerces results to a common type
• Document newly supported math and trig functions: CONVERT, DIVIDE
• Remove BLANK other function caveat
• Document newly supported table manipulation functions: CURRENTGROUP, GROUPBY, NATURALINNERJOIN
• Document newly supported miscellaneous function: GROUPCROSSAPPLY