Add migration phases pages

[Naarcha-AWS]

This PR consolidates the migration phases documentation for Migration Assistant into single pages and edits the Migration Console pages.

Checklist

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[github-actions]

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[sumobrian]

Sugested a change for consistency but no further reviews are needed.

[sumobrian]

Inconsistent casing. (As a side note, I know we use “Migration Assistant,” but since Migration Assistant is the name of a product, I think we can remove “the” in each of these occurrences. These changes should be applied consistently.)

[natebower]

@Naarcha-AWS Please see my comments and changes and let me know if you have any questions. Thanks!

[natebower]

Suggested change

	This command will result in the loss of any captured traffic data up to this point by the capture proxy and thus should be used with caution.
	This command will result in the loss of any traffic data captured by the capture proxy up to this point and thus should be used with caution.

[natebower]

Suggested change

	To clear non-system indexes from the target cluster that may have been created from testing, the following command can be executed.
	To clear non-system indexes from the target cluster that may have been created from testing, you can run the following command.

[natebower]

Line 188: "from" => "as a result of"?

[natebower]

Suggested change

	This command will result in the loss of all data on the target cluster and should be used with caution.
	This command will result in the loss of all data in the target cluster and should be used with caution.

[opensearch-trigger-bot]

The backport to 2.18 failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/backport-2.18 2.18
# Navigate to the new working tree
pushd ../.worktrees/backport-2.18
# Create a new branch
git switch --create backport/backport-8828-to-2.18
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 1fcf2785a8db8d67e7584f359d52e78e0ce96810
# Push it to GitHub
git push --set-upstream origin backport/backport-8828-to-2.18
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/backport-2.18

Then, create a pull request where the base branch is 2.18 and the compare/head branch is backport/backport-8828-to-2.18.