TS: getTransactionConfirmations won't work with Electrs

[nkuba]

The current implementation of getTransactionConfirmations won't work with Electrs, as verbose transaction details are not supported there (see: Blockstream/electrs#36 (comment)).

tbtc-v2/typescript/src/electrum.ts

Lines 190 to 205 in a9424d1

	// eslint-disable-next-line valid-jsdoc
	/**
	* @see {BitcoinClient#getTransactionConfirmations}
	*/
	getTransactionConfirmations(
	transactionHash: TransactionHash
	): Promise<number> {
	return this.withElectrum<number>(async (electrum: any) => {
	const transaction = await electrum.blockchain_transaction_get(
	transactionHash,
	true
	)
	return transaction.confirmations
	})
	}

We should implement a workaround to cover Electrs.
An example workaround was implemented in the Keep Client:
https://github.com/keep-network/keep-core/blob/d69e971fc734031111699f95eccc3bbbafe4345f/pkg/bitcoin/electrum/electrum.go#L163-L206