Read .rc files from bootstrap apexes

To start an early_hal service from a bootstrap vendor apex, init now
reads .rc files from bootstrap apexes as well.

In this change, perform_apex_config command is re-purposed to support
bootstrap mode. Now we have some similarity between two apexd calls:

- for bootstrap apexes (in the bootstrap mount namespace):

  exec_start apexd-bootstrap
  perform_apex_config --bootstrap

- for normal apexes (in the default mount namespace):

  restart apexd
  ...
  wait_for_prop apexd.status activated
  perform_apex_config

Note that some tasks in perform_apex_config are not needed in the
bootstrap.  For example, we don't need to create apexdata directories
for bootstrap apexes.

Bug: 290148081
Test: VendorApexHostTestCases
Change-Id: I8f683a4dcd7cd9a2466a4b1b417d84c025c37761
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 8f01d93..0d31cdc 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -74,9 +74,7 @@
     # become available. Note that this is executed as exec_start to ensure that
     # the libraries are available to the processes started after this statement.
     exec_start apexd-bootstrap
-
-    # Generate linker config based on apex mounted in bootstrap namespace
-    update_linker_config
+    perform_apex_config --bootstrap
 
     # These must already exist by the time boringssl_self_test32 / boringssl_self_test64 run.
     mkdir /dev/boringssl 0755 root root