Remove intermediate tasks from Bitcoindevkit group

This ensures they don't show up when using ./gradlew :jvm:tasks. The
only two tasks that will appear in the end will be buildJvmLib and
buildAndroidLib.

buildSrc/src/main/kotlin/org/bitcoindevkit/plugins/Enums.kt

@@ -0,0 +1,13 @@
+package org.bitcoindevkit.plugins
+
+enum class Arch {
+    AARCH64,
+    X86_64,
+    OTHER,
+}
+
+enum class OS {
+    MAC,
+    LINUX,
+    OTHER,
+}

buildSrc/src/main/kotlin/org/bitcoindevkit/plugins/generate-jvm-bindings.gradle.kts

@@ -0,0 +1,88 @@
+package org.bitcoindevkit.plugins
+
+val operatingSystem: OS = when {
+    System.getProperty("os.name").contains("mac", ignoreCase = true) -> OS.MAC
+    System.getProperty("os.name").contains("linux", ignoreCase = true) -> OS.LINUX
+    else -> OS.OTHER
+}
+val architecture: Arch = when (System.getProperty("os.arch")) {
+    "x86_64" -> Arch.X86_64
+    "aarch64" -> Arch.AARCH64
+    else -> Arch.OTHER
+}
+
+// register a task of type Exec called buildJvmBinary
+// which will run something like
+// cargo build --release --target aarch64-apple-darwin
+val buildJvmBinary by tasks.register<Exec>("buildJvmBinary") {
+    // group = "Bitcoindevkit"
+    // description = "Build the JVM binaries for the bitcoindevkit"
+
+    workingDir("${project.projectDir}/../bdk-ffi")
+    val cargoArgs: MutableList<String> = mutableListOf("build", "--release", "--target")
+
+    if (operatingSystem == OS.MAC && architecture == Arch.X86_64) {
+        cargoArgs.add("x86_64-apple-darwin")
+    } else if (operatingSystem == OS.MAC && architecture == Arch.AARCH64) {
+        cargoArgs.add("aarch64-apple-darwin")
+    } else if (operatingSystem == OS.LINUX) {
+        cargoArgs.add("x86_64-unknown-linux-gnu")
+    }
+
+    executable("cargo")
+    args(cargoArgs)
+
+    doLast {
+        println("Native library for bdk-jvm on ${cargoArgs.last()} successfully built")
+    }
+}
+
+// move the native libs build by cargo from bdk-ffi/target/.../release/
+// to their place in the bdk-jvm library
+val moveNativeJvmLib by tasks.register<Copy>("moveNativeJvmLib") {
+    // group = "Bitcoindevkit"
+    // description = "Move the native libraries to the bdk-jvm project"
+    dependsOn(buildJvmBinary)
+
+    var targetDir = ""
+    var resDir = ""
+    if (operatingSystem == OS.MAC && architecture == Arch.X86_64) {
+        targetDir = "x86_64-apple-darwin"
+        resDir = "darwin-x86-64"
+    } else if (operatingSystem == OS.MAC && architecture == Arch.AARCH64) {
+        targetDir = "aarch64-apple-darwin"
+        resDir = "darwin-aarch64"
+    } else if (operatingSystem == OS.LINUX) {
+        targetDir = "x86_64-unknown-linux-gnu"
+        resDir = "linux-x86-64"
+    }
+
+    from("${project.projectDir}/../bdk-ffi/target/$targetDir/release/libbdkffi.dylib")
+    into("${project.projectDir}/../jvm/src/main/resources/$resDir/")
+
+    doLast {
+        println("$targetDir native binaries for JVM moved to ./jvm/src/main/resources/$resDir/")
+    }
+}
+
+// generate the bindings using the bdk-ffi-bindgen tool
+// created in the bdk-ffi submodule
+val generateJvmBindings by tasks.register<Exec>("generateJvmBindings") {
+    // group = "Bitcoindevkit"
+    // description = "Building the bindings file for the bitcoindevkit"
+    dependsOn(moveNativeJvmLib)
+
+    workingDir("${project.projectDir}/../bdk-ffi")
+    executable("cargo")
+    args("run", "--package", "bdk-ffi-bindgen", "--", "--language", "kotlin", "--out-dir", "../jvm/src/main/kotlin")
+
+    doLast {
+        println("JVM bindings file successfully created")
+    }
+}
+
+tasks.register("buildJvmLib") {
+    group = "Bitcoindevkit"
+    description = "Aggregate task to build JVM library"
+    dependsOn(buildJvmBinary, moveNativeJvmLib, generateJvmBindings)
+}