[SPARK-27682][CORE][GRAPHX][MLLIB] Replace use of collections and methods that will be removed in Scala 2.13 with work-alikes

[srowen]

What changes were proposed in this pull request?

This replaces use of collection classes like MutableList and ArrayStack with workalikes that are available in 2.12, as they will be removed in 2.13. It also removes use of .to[Collection] as its uses was superfluous anyway. Removing collection.breakOut will have to wait until 2.13

How was this patch tested?

Existing tests

[srowen]

"pop" the first element

[SparkQA]

Test build #105333 has finished for PR 24586 at commit f70a5cc.

• This patch fails to build.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #105334 has finished for PR 24586 at commit e012cd5.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #105335 has finished for PR 24586 at commit ea39ea2.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #105336 has finished for PR 24586 at commit e81cb1a.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[MaxGekk]

LGTM

[skonto]

Another non breaking thing to migrate is: scala.collection.mutable.WrappedArray -> mutable.ArraySeq. WrappedArray is deprecated in 2.13 and ArraySeq is the replacement.
Thoughts about mapValues, sameElements, zip? ArrayBuilder.make seems ok we dont use ().
The harder I think is to[C[_]] unless we use the compat lib or in general create aliases for whatever we need.

[srowen]

WrappedArray is a good point. It's only deprecated, and not used in public APIs, and is trickier to avoid as we have a lot of code matching on it as the current type one gets from Scala. That may be one we accept as a deprecation while 2.12 and 2.13 are supported and remove it with 2.12 support.

[SparkQA]

Test build #105394 has finished for PR 24586 at commit 33b049b.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[srowen]

BTW I worked around to[C] by simply avoiding it. What are the other issues about mapValues, etc? We will most certainly do another pass or two before we can support Scala 2.13. When we're able to build for it I'm sure we will find a number of minor issues that remained. This is just addressing as much of the collections-related ones that are obvious and can be fixed easily.

[srowen]

Merged to master