fix(richtext-lexical): enable select inputs with ctrl+a or cmd+a (#12453)

Fixes #6871

To review this PR, use `pnpm dev lexical` and the auto-created document
in the `lexical fields` collection. Select any input within the blocks
and press `cmd+a`. The selection should contain the entire input.

I made sure that `cmd+a` still works fine inside the editor but outside
of inputs.

test/database/up-down-migration/migrations/20250528_153134.ts

@@ -1,4 +1,4 @@
-import type { MigrateDownArgs, MigrateUpArgs} from '@payloadcms/db-postgres';
+import type { MigrateDownArgs, MigrateUpArgs } from '@payloadcms/db-postgres'
 
 import { sql } from '@payloadcms/db-postgres'