[lexical-table] Bug Fix: Fix crash in $deleteCellHandler

[etrepum]

Description

In certain situations $deleteCellHandler will remove a table without fixing up the selection and also return false, which turns into a crash in the editor's command listener because the selection's anchor or focus is no longer connected to the root.

Closes #6581

Test plan

Before

1. Create a table
2. Remove the paragraph before the table
3. Select all from inside the table (anchor will be inside the table, focus will be outside the table)
4. Press delete
5. Crash

After

No crash

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
lexical	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 20, 2024 3:08am
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[github-actions]

size-limit report 📦

Path	Size
lexical - cjs	29.85 KB (0%)
lexical - esm	29.66 KB (0%)
@lexical/rich-text - cjs	38.3 KB (0%)
@lexical/rich-text - esm	31.55 KB (0%)
@lexical/plain-text - cjs	36.9 KB (0%)
@lexical/plain-text - esm	28.86 KB (0%)
@lexical/react - cjs	40.04 KB (0%)
@lexical/react - esm	32.91 KB (0%)

[ivailop7]

Thank you for your help on this one!