[FW][FIX] sheetview: pageUp/Down with frozen rows

[fw-bot]

Description

There was two issues with the commands SHIFT_VIEWPORT_UP/DOWN when some rows were frozen:

• the viewport was never scrolled all the way down to the last row with pageDown
• pageDown/Up scrolled more than a "page" (the size of the viewport)

This commit fixes both issues.

Also replaced calls from getActiveMainViewport to getMainInternalViewport
in the plugin SheetView as it needs slightly less computations.

Task: : 3847414

review checklist

• feature is organized in plugin, or UI components
• support of duplicate sheet (deep copy)
• in model/core: ranges are Range object, and can be adapted (adaptRanges)
• in model/UI: ranges are strings (to show the user)
• undo-able commands (uses this.history.update)
• multiuser-able commands (has inverse commands and transformations where needed)
• new/updated/removed commands are documented
• exportable in excel
• translations (_t("qmsdf %s", abc))
• unit tested
• clean commented code
• track breaking changes
• doc is rebuild (npm run doc)
• status is correct in Odoo

Forward-Port-Of: #3981

[robodoo]

Pull request status dashboard.

[fw-bot]

@hokolomopo @rrahir cherrypicking of pull request #3981 failed.

stdout:

Auto-merging src/plugins/ui_stateful/sheetview.ts
CONFLICT (content): Merge conflict in src/plugins/ui_stateful/sheetview.ts
Auto-merging tests/plugins/sheetview.test.ts

stderr:

08:59:31.475484 git.c:463               trace: built-in: git cherry-pick eee0c5c56123e8c4de562b8e95831e28a7f6b528
error: could not apply eee0c5c56... [FIX] sheetview: pageUp/Down with frozen rows
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".
----------
status:

Either perform the forward-port manually (and push to this branch, proceeding as usual) or close this PR (maybe?).

In the former case, you may want to edit this PR message as well.

⚠️ after resolving this conflict, you will need to merge it via @robodoo.

More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port

[hokolomopo]

@robodoo r+