Handle 'data' scheme downloads through WebKit's decisionHandler(.download)

[miasma13]

Task/Issue URL: https://app.asana.com/0/414709148257752/1208621179920770/f

Description:
When navigation should trigger download and is of data scheme handle it via decisionHandler(.download)

Steps to test this PR:

• test downloads on https://napuzba.com/data-url/ (ensure proper file name and extension)
• test website from https://app.asana.com/0/1206777341262243/1208605967462508/f following repro steps in https://app.asana.com/0/0/1208605967462508/1208619416618129/f

Definition of Done (Internal Only):

• Does this PR satisfy our Definition of Done?

Copy Testing:

• Use of correct apostrophes in new copy, ie ’ rather than '

Orientation Testing:

• Portrait
• Landscape

Device Testing:

• iPhone SE (1st Gen)
• iPhone 8
• iPhone X
• iPhone 14 Pro
• iPad

OS Testing:

• iOS 15
• iOS 16
• iOS 17

Theme Testing:

• Light theme
• Dark theme

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Internal references:

Software Engineering Expectations
Technical Design Template

[samsymons]

LGTM, thanks. Tested the provided test cases, as well as a range of different download types, including inline usage of data:.