[FLASK] Unblock personal_sign for snaps

[FrederikBolding]

Explanation

Add support for usage of personal_sign for snaps by using a legacy authorship header for this specific screen. Furthermore, SIWE is turned off for all snap requests.

This needs work from the snaps monorepo to be feature complete.

Progresses MetaMask/snaps#1551

[metamaskbot]

Builds ready [bd70d58]

• builds: chrome, firefox
• builds (beta): chrome
• builds (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
  • common: 0, 1, 2, 3, 4, 5
  • content-script: 0
  • contentscript: contentscript
  • disable-console: disable-console
  • inpage: inpage
  • policy-load: policy-load
  • sentry-install: sentry-install
  • ui: 0, 1, 10, 11, 12, 2, 3, 4, 5, 6, 7, 8, 9

Page Load Metrics (1594 ± 53 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	111	153	132	11	5
		domContentLoaded	1439	1816	1594	111	53
		load	1439	1816	1594	111	53
		domInteractive	1439	1816	1594	111	53

Bundle size diffs

• background: 0 Bytes (0.00%)
• ui: 271 Bytes (0.00%)
• common: 0 Bytes (0.00%)

[codecov]

Codecov Report

Merging #19998 (bd70d58) into develop (733391a) will increase coverage by 0.00%.
The diff coverage is 77.78%.

@@           Coverage Diff            @@
##           develop   #19998   +/-   ##
========================================
  Coverage    69.38%   69.38%           
========================================
  Files          987      987           
  Lines        37267    37271    +4     
  Branches     10008    10010    +2     
========================================
+ Hits         25854    25857    +3     
- Misses       11413    11414    +1     

Impacted Files	Coverage Δ
...t-original/signature-request-original.component.js	59.79% <75.00%> (-0.21%)	⬇️
ui/pages/confirm-signature-request/index.js	63.08% <80.00%> (+1.17%)	⬆️