Take core 7.4.0, and format sheet cells and align paragraphs

[andiwand]

Summary

This PR takes core v7.4.0 and uses its new features.

• Sheet formatting. The strip now shows over a sheet. It has the same tools as a document, but it has a fill in place of the highlight. In lite, the fill is the free tool, as the highlighter is in a document.
• Paragraph alignment. Both strips get an alignment tool. A tap opens left, center, right and justify, under the tool. A sheet does not get justify, because a cell has no justify. The icon shows the alignment of the selection.
• HtmlConfig.hostMessageHandler. The page sends every odr.on* callback to PageView.postMessage. This PR deletes editing-bridge.js and its injection in onPageFinished. The callbacks are now in place before the page's scripts run, not after the load finishes.
• HtmlConfig.sheetEditOnClick and pdfAnnotationMarkOnSelection. These replace the two calls that the injected script made after each load.

Changes in the core that come with the version and need no work in the app:

• Sheet fills show their real colors, and keep them in night mode.
• A typed space shows, and a save keeps spaces as spaces.
• External images do not load, and only a link with a navigable scheme leaves the page. PageView.shouldOverrideUrlLoading already gives such a link to another app. I keep allowExternalContent off, because no document leaves the device.

Not used: PdfFile.permissions and pdfEnforcePermissions. pdf.js keeps them off by default too. Enforcing them would block copy and print on some pdfs. That is a product decision, so I did not make it here.

The new strings are in English only. Run scripts/translate-app.py before the release.

Test plan

• spotlessCheck assembleDebug lintProDebug testProDebugUnitTest
• connectedProDebugAndroidTest: 98 of 98 pass on Pixel_6_Pro (API 31)
• connectedLiteDebugAndroidTest: 98 of 98 pass on Pixel_6_Pro (API 31)
• The new test aSheetCellTakesAFill pins a cell and taps the fill. It checks that the page logs a setCellStyle op, and that the edit reaches the app through postMessage.
• A look at the alignment row and the fill palette on a device

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