Export linker scripts in the bazel build. (#1944)

* Export linker scripts in the bazel build.

Make the rp2040 and rp2350 linker scripts available in downstream
projects bazel builds.

* Move exports_files below the package declaration.

Author: davexroth

src/rp2_common/pico_crt0/rp2040/BUILD.bazel

@@ -1,5 +1,14 @@
 package(default_visibility = ["//visibility:public"])
 
+exports_files(
+    [
+        "memmap_blocked_ram.ld",
+        "memmap_copy_to_ram.ld",
+        "memmap_default.ld",
+        "memmap_no_flash.ld",
+    ]
+)
+
 # It's possible to set linker scripts globally or on a per-binary basis.
 #
 # Setting globally:

src/rp2_common/pico_crt0/rp2350/BUILD.bazel

@@ -1,5 +1,13 @@
 package(default_visibility = ["//visibility:public"])
 
+exports_files(
+    [
+        "memmap_copy_to_ram.ld",
+        "memmap_default.ld",
+        "memmap_no_flash.ld",
+    ]
+)
+
 # It's possible to set linker scripts globally or on a per-binary basis.
 #
 # Setting globally: