0365 Add type assertions to painless scripts

[leehinman]

What does this PR do?

• Adds type assertion of Map when containsKey() is used
• Adds type assertion of List when accessing as array

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
  - [ ] If I'm introducing a new feature, I have modified the Kibana version constraint in my package's manifest.yml file to point to the latest Elastic stack release (e.g. ^7.13.0).

How to test this PR locally

elastic-package test

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Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

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Build stats

• Start Time: 2021-09-10T20:18:01.504+0000

• Duration: 16 min 34 sec

• Commit: dbb7fac

Test stats 🧪

Test	Results
Failed	0
Passed	26
Skipped	0
Total	26

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[andrewkroh]

LGTM. Do we have any log samples to test with where the data within AlertLinks are not objects?

[leehinman]

LGTM. Do we have any log samples to test with where the data within AlertLinks are not objects?

No, unfortunately I haven't gotten event.originals from the case yet. Will update with test cases when/if we get them. These changes were based off the following error.messages

dynamic method [java.lang.String, containsKey/1] not found
Provided Grok expressions do not match field value: [AB1CD23EF4567 (10.10.10.10)\r]
Attempting to address a non-array-like type [java.lang.String] as an array.