perf: FMP spans for tokens and nfts tabs

[MajorLift]

Description

Approach

Defines the following custom spans:

• 'Account Overview - Asset List Tab - First Contentful Paint'
• 'Account Overview - Nfts Tab - First Meaningful Paint'
• Refactored object ACCOUNT_OVERVIEW_TAB_KEY_TO_TRACE_NAME_MAP into ACCOUNT_OVERVIEW_TAB_KEY_TO_TRACE_NAMES_ARRAY_MAP.

Behavior

• Triggers a) when an account list item is clicked in the account list menu component, or b) when an account overview tab (e.g. "Tokens", "NFTs", "Activity") is clicked.
• Terminates:
  • `'Account Overview - Asset List Tab - First Contentful Paint':
    • Component renders.
  • 'Account Overview - Nfts Tab - First Meaningful Paint':
    • If there is no data to display, the loading spinner disappears, and the appropriate filler content renders.
    • Otherwise, the first batch of NFT content is displayed, regardless of whether the loading spinner has disappeared or not.

Results

Related issues

Fixes:

Manual testing steps

1. Click one or more of the account overview tabs ("Tokens", "NFTs", "Activity").
2. Click Account Menu
3. Switch account and repeat.

• Add accounts as necessary.
• For load testing, add whale account(s) using the experimental "Watch Account" feature.

Screenshots/Recordings

Before

After

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Extension Coding Standards.
• I've completed the PR template to the best of my ability
• I’ve included tests if applicable
• I’ve documented my code using JSDoc format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

[github-actions]

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