boot(api): Add framework-nfc to NFC apex

Adding a conditional boot entry for framework-nfc.jar to be delivered
via NFC apex.

Also, rename the existing soong_config namespace for bootclasspath
entries to more generic "bootclasspath" (modified the existing usage to
match).

Bug: 303286040
Test: Compiles (with RELEASE_PACKAGE_NFC_STACK=NfcNci)
Test: Compiles (with RELEASE_PACKAGE_NFC_STACK=com.android.nfcservices)
Test: Device boots up after flashing
Test: atest CtsNfcTestCases
Change-Id: If170240fe60120a61dcceb68f9c581261aeee49f
diff --git a/nfc/Android.bp b/nfc/Android.bp
index 5d1404a..87da299 100644
--- a/nfc/Android.bp
+++ b/nfc/Android.bp
@@ -70,6 +70,10 @@
     lint: {
         strict_updatability_linting: true,
     },
+    apex_available: [
+        "//apex_available:platform",
+        "com.android.nfcservices",
+    ],
 }
 
 filegroup {