feat: Return values for block manipulation methods

[matthewlipski]

This PR adds return values for the following BlockNoteEditor methods:

// Returns the blocks after being inserted
insertBlocks(...): Block[]

// Returns the updated block
updateBlock(...): Block

// Returns the blocks that were removed
removeBlocks(...): Block[]

// Returns both the blocks that were removed and the blocks after being inserted
replaceBlocks(...): {
  insertedBlocks: Block[];
  removedBlocks: Block[];
}

Closes #410

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Name	Status	Preview	Updated (UTC)
blocknote	✅ Ready (Inspect)	Visit Preview	Jan 3, 2024 3:48pm
blocknote-website	✅ Ready (Inspect)	Visit Preview	Jan 3, 2024 3:48pm

[sahilpohare]

Could we have this merged?