Add workflow dispatch to all test workflows

.github/workflows/test-android.yaml

@@ -1,5 +1,6 @@
 name: Test Android
 on:
+  workflow_dispatch:
   push:
     paths:
       - "bdk-ffi/**"

.github/workflows/test-jvm.yaml

@@ -1,5 +1,6 @@
 name: Test Kotlin/JVM
 on:
+  workflow_dispatch:
   push:
     paths:
       - "bdk-ffi/**"

.github/workflows/test-python.yaml

@@ -1,5 +1,6 @@
 name: Test Python
 on:
+  workflow_dispatch:
   push:
     paths:
       - "bdk-ffi/**"

.github/workflows/test-swift.yaml

@@ -1,5 +1,6 @@
 name: Test Swift
 on:
+  workflow_dispatch:
   push:
     paths:
       - "bdk-ffi/**"