[rapid7_insightvm] Add nested fields to asset and asset_vulnerability data streams

[brijesh-elastic]

Proposed commit message

rapid7_insightvm: Add nested fields to asset and asset_vulnerability data streams

The `credential_assessments`, `tags`, and `unique_identifiers` fields were originally defined as arrays.
To improve searchability and allow each object to be queried independently of one another, this PR
introduced new nested field variations for each.

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.
• I have verified that Kibana version constraints are current according to guidelines.
• I have verified that any added dashboard complies with Kibana's Dashboard good practices

How to test this PR locally

• Clone integrations repo.
• Install elastic package locally.
• Start elastic stack using elastic-package.
• Move to integrations/packages/rapid7_insightvm directory.
• Run the following command to run tests.

elastic-package test -v

Related issues

• Closes Rapid7 InsightVM [rapid7_insightvm]: Unknown (array) fields #17038

[elasticmachine]

Pinging @elastic/security-service-integrations (Team:Security-Service Integrations)

[github-actions]

Vale Linting Results

Summary: 4 warnings found

⚠️ Warnings (4)

File	Line	Rule	Message
packages/rapid7_insightvm/docs/README.md	263	Elastic.QuotesPunctuation	Place punctuation inside closing quotation marks.
packages/rapid7_insightvm/docs/README.md	265	Elastic.QuotesPunctuation	Place punctuation inside closing quotation marks.
packages/rapid7_insightvm/docs/README.md	548	Elastic.QuotesPunctuation	Place punctuation inside closing quotation marks.
packages/rapid7_insightvm/docs/README.md	550	Elastic.QuotesPunctuation	Place punctuation inside closing quotation marks.

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The Vale linter checks documentation changes against the Elastic Docs style guide.

To use Vale locally or report issues, refer to Elastic style guide for Vale.

[elastic-vault-github-plugin-prod]

🚀 Benchmarks report

To see the full report comment with /test benchmark fullreport

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 88412ac

cc @brijesh-elastic

[efd6]

This is the implementation that the user asked for. An alternative would be to construct a map of name to type, but I think risks clobbering data if the same name appears twice, and if a user wants that behaviour it is easy to implement in a @custom pipeline.

[efd6]

I disagree with the Vale linter here; in normal English punctuation rules, what it says is correct, but in the context of quoting a value that is a string literal it is heading for confused users.