DOCSP-37354: Add Flutter dynamic.get methods

[cbullinger]

Pull Request Info

Jira ticket: https://jira.mongodb.org/browse/DOCSP-37354

• Data Types - Flutter SDK: Document dynamic.getList(), dynamic.getMap(), and dynamic.getSet() methods.
• Additional snippet and schema formatting corrections

Reminder Checklist

Before merging your PR, make sure to check a few things.

• Did you tag pages appropriately?
  • genre
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• Describe your PR's changes in the Release Notes section
• Create a Jira ticket for related docs-app-services work, if any

Release Notes

• Flutter SDK
  • Realm/Realm Database/Model Data/Data Types: Update code examples with 'dynamic.getList()', 'dynamic.getSet()', and 'dynamic.getMap()' methods

Review Guidelines

REVIEWING.md

[github-actions]

Readability for Commit Hash: 08e4880

You can see any previous Readability scores (if they exist) by looking
at the comment's history.

Readability scores for changed documents:

• source/sdk/flutter/realm-database/model-data/data-types: Grade Level: 7.9, Reading Ease: 59.5

For Grade Level, aim for 8 or below.

For Reading Ease scores, aim for 60 or above:

Score	Difficulty
90-100	Very Easy
80-89	Easy
70-79	Fairly Easy
60-69	Medium
50-59	Fairly Hard
30-49	Hard
0-29	Very Hard

For help improving readability, try Hemingway App.

[cbullinger]

Autobuilder failed but it's unrelated to this PR - all errors are related to the new :orphan: directive (that I'm assuming will get cleaned up in a separate PR)

[dacharyc]

LGTM!

[docs-builder-bot]

✨ Staging URL: https://preview-mongodbmongodb.gatsbyjs.io/realm/master/

🪵 Logs

• job log: ccac7a6d430ffbe27c674f04fbb7d81d3ff4aca4