assets controllers deprecation

[bergarces]

Explanation

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Low Risk
Annotation-only change with no runtime logic; low risk aside from IDE deprecation noise for consumers still on the old controllers.

Overview
Documents the migration from the legacy split assets stack to unified AssetsController in @metamask/assets-controller.

@metamask/assets-controllers adds a Deprecated changelog entry and applies a shared JSDoc @deprecated tag across eleven legacy controllers: AccountTrackerController, CurrencyRateController, MultichainAssetsController, MultichainAssetsRatesController, MultichainBalancesController, RatesController, TokenBalancesController, TokenListController, TokenRatesController, and TokensController. Coverage includes exported state/types, messenger action types (including auto-generated *-method-action-types files), and public instance methods.

TokenListController polling helpers (start, restart, stop, destroy, etc.) now use the same deprecation wording as the rest of the package instead of generic “new polling approach” notes.

There is no functional or API behavior change in this PR—only TypeScript/editor deprecation surfacing and changelog documentation. The unreleased section also bumps @metamask/network-enablement-controller to ^5.3.0.

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