LVGL: add Textarea actions and owned ButtonMatrix maps

[AwangYes]

Summary

This is the framework part of a coordinated Studio Textarea / ButtonMatrix update.

• Append action IDs 65–73 without reordering 0–64: six Textarea actions, ButtonMatrix Get Selected Button, Get Button Text and Set Map.
• Keep Textarea and ButtonMatrix getter results and converted string arguments alive independently of widgets/temporary Values.
• Copy ButtonMatrix maps and labels, release them on replacement/deletion, preserve text-update controls, and validate widget types/counts/row-width bounds before dispatch.
• Successful Set Map detaches original widget text bindings so later ticks cannot restore a default symbol over replacement text. Failed replacement leaves bindings active; new widgets start with active bindings. No new action IDs or UI options are introduced for this fix.
• Return cleanly when ObjectAllocator receives a null allocation instead of invoking placement new at address zero.
• Expose the two map/text helpers for Studio's runtime and generated code. The C-compatible implementation is also reused by generated projects without Flow.

Validation

• Five real LVGL versions (8.4.0, 9.2.2, 9.3.0, 9.4.0, 9.5.0): expression bytecode → action dispatch → actual LVGL objects.
• Getter ownership, string-conversion lifetime, password mode/bullet with ASCII and UTF-8, selection/NONE, complete map/ctrl replacement and 500 repeated replacements.
• C helper tests inject allocation/event-registration failures and exercise aliasing, row limits, bubbled deletion and externally replaced static maps.
• Generated amalgamation compiled and run under ASan/UBSan with LVGL 8.4.0 and 9.5.0.
• Binding ownership regression: symbol-to-text replacement, 500 replacements, allocation/event failures and widget recreation. Companion CI: https://github.com/AwangYes/studio-wasm-libs/actions/runs/35080585574
• Allocator CI: https://github.com/AwangYes/eez-framework/actions/runs/35067456366

The integration tests/build tooling live in the accompanying studio-wasm-libs change; this repository's small CI job only exercises the allocator guard. LVGL's own allocation/assert behavior is not changed.

Integration order

Merge the framework change first, then update the studio-wasm-libs submodule pin and regenerate its amalgamation plus five engines, then consume those same artifacts in Studio. Studio's Set Map uses the existing complete Buttons editor, not a new raw-map parameter or UI style. All new actions require the matching runtime, so this is one feature delivery rather than a Set Map-only follow-up.

Companion PRs: eez-open/studio-wasm-libs#1 and eez-open/studio#1068.