rpc: add raw_tx field to BumpFee response

This commit adds an optional include_raw_tx field to BumpFeeRequest
and a raw_tx field to BumpFeeResponse. When include_raw_tx is set to
true, the RPC will wait for the sweep transaction to be created and
return its hex-encoded raw transaction.

This allows users to manually broadcast transactions in cases where
they don't propagate automatically, addressing issue #8470.

Changes:
- Add include_raw_tx bool field to BumpFeeRequest proto
- Add raw_tx string field to BumpFeeResponse proto
- Modify BumpFee implementation to optionally wait for sweep result
- Update sweepNewInput to return result channel
- Add --include_raw_tx flag to lncli wallet bumpfee command

Closes #8470

Author: federicociro

cmd/commands/walletrpc_active.go

@@ -316,6 +316,14 @@ var bumpFeeCommand = cli.Command{
 	required. When the deadline is reached, ALL the budget will be spent as
 	fee.`,
 		},
+		cli.BoolFlag{
+			Name: "include_raw_tx",
+			Usage: `
+	Whether to include the raw transaction hex in the response. This is
+	useful for cases where the transaction does not propagate and the caller
+	wants to manually broadcast it. Note that setting this to true will
+	cause the command to block until the sweep transaction is created.`,
+		},
 	},
 	Action: actionDecorator(bumpFee),
 }
@@ -359,6 +367,7 @@ func bumpFee(ctx *cli.Context) error {
 		Budget:        ctx.Uint64("budget"),
 		SatPerVbyte:   ctx.Uint64("sat_per_vbyte"),
 		DeadlineDelta: uint32(ctx.Uint64("deadline_delta")),
+		IncludeRawTx:  ctx.Bool("include_raw_tx"),
 	})
 	if err != nil {
 		return err