feat(cdk/coercion): add coercion for string arrays

[annieyw]

redo of #17523 because there are now too many merge conflicts to merge cleanly

[crisbeto]

LGTM, but the API goldens check is failing.

[mmalerba]

LGTM

[jelbourn]

@annieyw can you amend your commit to include the original PR author as a co-author?

[googlebot]

We found a Contributor License Agreement for you (the sender of this pull request), but were unable to determine that you authored the commits in this PR. Maybe you used a different email address in the git commits than was used to sign the CLA? If someone else authored these commits, then please add them to this pull request and have them confirm that they're okay with them being contributed to Google. If there are co-authors, make sure they're formatted properly.

In order to pass this check, please resolve this problem and then comment@googlebot I fixed it... If the bot doesn't comment, it means it doesn't think anything has changed.

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[googlebot]

A Googler has manually verified that the CLAs look good.

(Googler, please make sure the reason for overriding the CLA status is clearly documented in these comments.)

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[annieyw]

Original author signed cla on original PR.

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