Add Support for Additional DataFrame Functionality

[grundprinzip]

The DataFrame still has lots of missing functions that need to be implemented. This is the umbrella item for that.

Most of them should be relatively mechanical, but some require some additional work.

Method	Support
agg	✅
alias	✅
approxQuantile	✅
cache	✅
checkpoint	❌
coalesce	✅
colRegex	✅ (OfDFWithRegex)
collect	✅
columns	✅
corr	✅
count	✅
cov	✅
createGlobalTempView	✅
createOrReplaceGlobalTempView	✅
createOrReplaceTempView	✅
createTempView	✅
crossJoin	✅
crosstab	✅
cube	✅
describe	✅
distinct	✅
drop	✅
dropDuplicates	✅
dropDuplicatesWithinWatermark	❌
dropna	✅
dtypes	❌
exceptAll	✅
executionInfo	❌
explain	✅
fillna	✅
filter	✅
first	✅
foreach	➖ (needs native UDFs)
foreachPartition	➖ (needs native UDFs)
freqItems	✅
groupBy	✅ (some restrictions apply)
head	✅
hint	❌
inputFiles	❌
intersect	✅
intersectAll	✅
isEmpty	✅
isLocal	❌
isStreaming	❌
is_cached	❌
join	✅
limit	✅
localCheckpoint	❌
mapInArrow	➖ (needs native UDFs)
mapInPandas	➖ (needs native UDFs)
melt	✅
mergeInto	❌
na	✅
observe	❌
offset	✅
orderBy	✅
pandas_api	➖
persist	✅
printSchema	❌
randomSplit	✅
rdd	➖
registerTempTable	❌
repartition	✅
repartitionByRange	✅
replace	✅
rollup	✅
sameSemantics	✅
sample	✅
sampleBy	❌
schema	✅
select	✅
selectExpr	✅
semanticHash	✅
show	✅
sort	✅
sortWithinPartitions	✅
sparkSession	❌
stat	✅
storageLevel	✅
subtract	✅
summary	✅
tail	✅
take	✅
to	❌
toArrow	✅
toDF	❌
toJSON	❌
toLocalIterator	❌
toPandas	➖
transform	❌
union	✅
unionAll	✅
unionByName	✅
unpersist	✅
unpivot	✅
where	✅
withColumn	✅
withColumnRenamed	✅
withColumns	✅
withColumnsRenamed	✅
withMetadata	✅
withWatermark	✅
write	✅
writeStream	❌
writeTo	❌