[FIX] composer: topbar composer z-index

[hokolomopo]

Description

The topbar composer has a big z-index, so its formula assistant is displayed above the rest.

But this z-index is useless when the composer is not focused. In fact, it causes problems in further versions where we end up with grid popovers being displayed below the composer.

Also the css to color the border blue when the composer is focused wasn't working.

Task: 4246966

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

[robodoo]