Update HeroImage to match the BigIcon component from Compound.

[pixlwave]

HeroImage is now completely in line with the Figma (inc renaming to BigIcon). It is still in the EX project for now to be less disruptive as this PR feels far reaching enough already. We can move it across in a following PR.

This is the iOS equivalent to element-hq/element-x-android#3719

[github-actions]

	Warnings
⚠️	Some of the commits are missing ticket numbers. Please consider squashing all commits that don't have a tracking number.
⚠️	You seem to have made changes to views. Please consider adding screenshots.

Generated by 🚫 Danger Swift against 44685ea

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[stefanceriu]

👏 🚀 👏

[codecov]

❌ 2 Tests Failed:

Tests completed	Failed	Passed	Skipped
847	2	845	0

View the top 1 failed tests by shortest run time

PreviewTests test_formButtonStyles()

Stack Traces | 60s run time

Test exceeded execution time allowance of 1 minute (see `-[XCTestCase executionTimeAllowance]`)

View the full list of 1 ❄️ flaky tests

PreviewTests test_loginScreen()

Flake rate in main: 27.41% (Passed 286 times, Failed 108 times)

Stack Traces | 4.08s run time

failed - Snapshot "matrix.org" does not match reference.

@−
"file:.../__Snapshots__/PreviewTests/test_loginScreen-iPhone-16-pseudo.matrix-org.png"
@+
"file:.../tmp/PreviewTests/test_loginScreen-iPhone-16-pseudo.matrix-org.png"

To configure output for a custom diff tool, use 'withSnapshotTesting'. For example:

    withSnapshotTesting(diffTool: .ksdiff) {
      // ...
    }

The percentage of pixels that match 0.8482666 is less than required 1.0
The lowest perceptual color precision 0.39937502 is less than required 0.98 (.../PreviewTests/Sources/PreviewTests.swift:84)

To view individual test run time comparison to the main branch, go to the Test Analytics Dashboard