[CALCITE-6812] Support base64 and unbase64 functions for Hive #14721

Job	Run time
Windows (JDK 21)	15m 56s
Windows (JDK 8)	16m 51s
Linux (JDK 8, oldest Guava, America/New_York Timezone)	10m 58s
Windows (JDK 17)	14m 59s
Linux (JDK 11, Pacific/Chatham Timezone)	10m 24s
Linux (JDK 21)	10m 25s
Linux (JDK 17)	10m 42s
Linux (JDK 8, latest Guava, America/New_York Timezone)	12m 17s
ErrorProne (JDK 11, latest Guava)	4m 1s
Linux (JDK 11, Avatica main)	12m 39s
CheckerFramework (JDK 11)	11m 1s
CheckerFramework (JDK 11, oldest Guava)	10m 50s
Linux (JDK 23)	10m 25s
macOS (JDK 21)	35m 24s
Druid Tests	7m 3s
Linux (JDK 8) Slow Tests	0s
	3h 13m 55s

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