init: Unify kernel bootconfig parser with libfs_mgr

Right now there are two bootconfig parsers that gets linked into `init`.
One is from libinit itself and the other is from libfs_mgr.

The one in libinit removes all space characters between list elements,
so `key = "val1", "val2"` gets unquoted and squeezed into:
  `key=val1,val2`
The one in libfs_mgr doesn't remove spaces, it only unquotes:
  `key=val1, val2`

The libinit behavior is due to existing systems (such as sysprop)
expect the config value to be in the same format as kernel cmdline.
(aosp/1757971)
THe libfs_mgr behavior is due to the `androidboot.boot_device[s]`
format explicitly allows quoted comma appear in its list value, thus
relies on space, not comma, as the list value delimeter.

This commit merges the two parsers into libfs_mgr. Since all usages in
libfs_mgr besides `boot_device[s]` do not care about how list value are
delimited, and most usages in init expects the bootconfig value format
to be the same format as cmdline. We just special case the
`boot_device` scenario.

Also harden the test cases to cover all the different config value
format and expected result.

Note:
The format of kernel bootconfig is described here
https://docs.kernel.org/admin-guide/bootconfig.html

Bug: 293695109
Test: CtsFsMgrTestCases
Change-Id: I42b9bf626e8de38a60e8e09fac0693126b7efd91
diff --git a/init/reboot_utils.cpp b/init/reboot_utils.cpp
index e6b868e..547b186 100644
--- a/init/reboot_utils.cpp
+++ b/init/reboot_utils.cpp
@@ -27,6 +27,7 @@
 #include <android-base/properties.h>
 #include <android-base/strings.h>
 #include <cutils/android_reboot.h>
+#include <fs_mgr.h>
 #include <unwindstack/AndroidUnwinder.h>
 
 #include "capabilities.h"
@@ -48,13 +49,9 @@
 
     const std::string kInitFatalPanicParamString = "androidboot.init_fatal_panic";
     if (cmdline.find(kInitFatalPanicParamString) == std::string::npos) {
-        init_fatal_panic = false;
-        ImportBootconfig(
-                [kInitFatalPanicParamString](const std::string& key, const std::string& value) {
-                    if (key == kInitFatalPanicParamString && value == "true") {
-                        init_fatal_panic = true;
-                    }
-                });
+        std::string value;
+        init_fatal_panic = (android::fs_mgr::GetBootconfig(kInitFatalPanicParamString, &value) &&
+                            value == "true");
     } else {
         const std::string kInitFatalPanicString = kInitFatalPanicParamString + "=true";
         init_fatal_panic = cmdline.find(kInitFatalPanicString) != std::string::npos;
@@ -68,11 +65,7 @@
     const std::string kRebootTargetString = "androidboot.init_fatal_reboot_target";
     auto start_pos = cmdline.find(kRebootTargetString);
     if (start_pos == std::string::npos) {
-        ImportBootconfig([kRebootTargetString](const std::string& key, const std::string& value) {
-            if (key == kRebootTargetString) {
-                init_fatal_reboot_target = value;
-            }
-        });
+        android::fs_mgr::GetBootconfig(kRebootTargetString, &init_fatal_reboot_target);
         // We already default to bootloader if no setting is provided.
     } else {
         const std::string kRebootTargetStringPattern = kRebootTargetString + "=";