fix: personal sign message - decode message to UTF-8 string only if it is valid UTF-8

[jpuri]

Description

Converts personal sign message to UTF-8 string only if it can be converted to valid UTF-8 string.

Related issues

Fixes: #3931

Manual testing steps

1. Send personal sign request to extension with message string 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470
2. Check on confirmation page that it is displayed as UTF-8 string

Screenshots/Recordings

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]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[metamaskbot]

Builds ready [439de89]

• builds: chrome, firefox
• builds (beta): chrome
• builds (flask): chrome, firefox
• builds (MMI): chrome, firefox
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• build viz: Build System
• mv3: Background Module Init Stats
• mv3: UI Init Stats
• mv3: Module Load Stats
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• code coverage: Report
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4, 5, 6
  • common: 0, 1, 10, 11, 12, 2, 3, 4, 5, 6, 7, 8, 9
  • content-script: 0
  • offscreen: 0
  • ui: 0, 1, 10, 11, 12, 2, 3, 4, 5, 6, 7, 8, 9

Page Load Metrics (1636 ± 50 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	315	1819	1566	303	145
		domContentLoaded	1417	1817	1609	106	51
		load	1436	1823	1636	105	50
		domInteractive	22	107	42	25	12
		backgroundConnect	8	62	30	19	9
		firstReactRender	16	84	41	25	12
		getState	5	53	13	14	7
		initialActions	0	1	0	0	0
		loadScripts	979	1329	1186	90	43
		setupStore	6	56	11	11	5
		uiStartup	1622	2046	1855	110	53

Bundle size diffs

• background: 0 Bytes (0.00%)
• ui: 314 Bytes (0.00%)
• common: 0 Bytes (0.00%)

[matthewwalsh0]

Minor, is it possible to include false cases?

[jpuri]

yep I will include it in following PR