[IMP] *: apply new icon implementation globally
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This commit is a follow-up to odoo/odoo#273606.

It applies the new icon implementation across the entire codebase,
replacing almost all legacy icon usages.

Previous patterns such as `class="oi oi-fw oi-arrow-left"` or
`class="fa fa-fw fa-arrow-left"` are migrated to the new format
using `class="oi oi-fw"` with the data-icon attribute (e.g.,
`data-icon="west"`), ensuring consistency with the Material
Symbols-based system.

Community PR: odoo/odoo#256840

task-5901783

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[IMP] web_{enterprise, studio}: adapt icon selector for Material Symbols
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With the switch to Material Symbols as the icon set, the app/menu icon
pickers and the various places that render web icons no longer rely on
Font Awesome classes. The FontAwesomeIconSelector component is renamed to
the StudioIconSelector and now sources its choices from the html_editor
MediaDialog icon selector (via initFonts) instead of the removed
getFontAwesomeIcons util. Icons are rendered with the `oi` class and a
`data-icon` attribute holding the Material Symbols name rather than a
composed class string, and the st full icon
name (no more stripping the `fa ` prefix).

Templates and components across web_enterprise (home menu, navbar) and
web_studio (icon creator, editor  button box
dialog) are updated accordingly, the icon_selector asset is added to the
Studio minimal bundle, and the reusted to use
Material Symbols names.

task-5901783