Warn, not panic, on invalid fonts (#22491)

# Objective

Fix panics due to invalid legacy fonts that we can't generate glyph
images from.

Fixes #22475

## Solution
* In `text_system` and `update_text2d_layout`, instead of panicking on
`TextError::FailedToGetGlyphImage`, `warn_once` and clear the text
layout.

* Given an invalid font, Cosmic Text returns an invalid text layout with
infinite text bounds. If Cosmic Text returns non-finite bounds, return a
zero size from the `buffer_dimensions` function.

* Added a `get_face_details` method to `CosmicFontSystem` to provide
better info for the warning messages.

`buffer_dimensions` probably should be reworked to return a `Result`,
with the text systems emitting a warning on invalid layout bounds. Not
so important though, left for a follow up.

## Testing

The `system_fonts` example should no longer panic now. Instead the text
with the invalid font is not rendered:

<img width="869" height="166" alt="system-fonts-list-fixed"
src="https://github.com/user-attachments/assets/a05cab45-68d2-453b-8fa6-16ec5b6bba76"
/>

One of the problematic fonts:
https://github.com/justrajdeep/fonts/blob/master/NISC18030.ttf

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>