feat: use FeeRate type in TxBuilder

bdk-android/lib/src/androidTest/kotlin/org/bitcoindevkit/LiveTxBuilderTest.kt

@@ -21,7 +21,7 @@ class LiveTxBuilderTest {
         val recipient: Address = Address("tb1qrnfslnrve9uncz9pzpvf83k3ukz22ljgees989", Network.TESTNET)
         val psbt: PartiallySignedTransaction = TxBuilder()
             .addRecipient(recipient.scriptPubkey(), 4200uL)
-            .feeRate(2.0f)
+            .feeRate(FeeRate.fromSatPerVb(2.0f))
             .finish(wallet)
 
         println(psbt.serialize())
@@ -49,7 +49,7 @@ class LiveTxBuilderTest {
 
         val psbt: PartiallySignedTransaction = TxBuilder()
             .setRecipients(allRecipients)
-            .feeRate(4.0f)
+            .feeRate(FeeRate.fromSatPerVb(4.0f))
             .changePolicy(ChangeSpendPolicy.CHANGE_FORBIDDEN)
             .enableRbf()
             .finish(wallet)

bdk-android/lib/src/androidTest/kotlin/org/bitcoindevkit/LiveWalletTest.kt

@@ -49,7 +49,7 @@ class LiveWalletTest {
 
         val psbt: PartiallySignedTransaction = TxBuilder()
             .addRecipient(recipient.scriptPubkey(), 4200uL)
-            .feeRate(4.0f)
+            .feeRate(FeeRate.fromSatPerVb(4.0f))
             .finish(wallet)
 
         println(psbt.serialize())

bdk-android/lib/src/androidTest/kotlin/org/bitcoindevkit/OfflineDescriptorTest.kt

@@ -4,7 +4,6 @@ import kotlin.test.Test
 import kotlin.test.assertEquals
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import org.junit.runner.RunWith
-import kotlin.test.assertEquals
 
 @RunWith(AndroidJUnit4::class)
 class OfflineDescriptorTest {

bdk-android/lib/src/androidTest/kotlin/org/bitcoindevkit/OfflineWalletTest.kt

@@ -3,6 +3,7 @@ package org.bitcoindevkit
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertTrue
+import kotlin.test.assertFalse
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import org.junit.runner.RunWith