Optimize IMMS.MyPackageMonitor more

This CL is a follow up CL to my previous CL [1] that aimed to reduce
false positives in InputMethodManagerService.MyPackageMonitor when
deciding if InputMethodManagerService (IMMS) needs to rebuild the list
of enabled IMEs or not.

Currently IMMS.MyPackageMonitor#onSomePackagesChanged() gets called
back to trigger IMMS#buildInputMethodListLocked() when either the
following rule A or B is fulfiled.

 A. Intent with one of the following actions for any package name:
    - ACTION_PACKAGE_ADDED
    - ACTION_PACKAGE_REMOVED
    - ACTION_EXTERNAL_APPLICATIONS_AVAILABLE
    - ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE
    - ACTION_PACKAGES_SUSPENDED
    - ACTION_PACKAGES_UNSUSPENDED
 B. ACTION_PACKAGE_CHANGED with a package that is included in the
    known IME package list, which can be obtained from PackageManager.

The previous CL [1] addressed Bug 28181208 by introducing the rule B,
but we can actually apply the same optimization for A, except for one
false negative case where an appearing package that is not in the
known IME package list actually contains one or more
InputMethodService.

In short, we can reduce false positives by replacing the above two
rules with the following two rules.

 A. Intent with one of the following actions for any package name that
    is in the known IME package list:
    - ACTION_PACKAGE_ADDED
    - ACTION_PACKAGE_CHANGED
    - ACTION_PACKAGE_REMOVED
    - ACTION_EXTERNAL_APPLICATIONS_AVAILABLE
    - ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE
    - ACTION_PACKAGES_SUSPENDED
    - ACTION_PACKAGES_UNSUSPENDED
 B. Intent with one of the following actions for any package that
    implements at least one InputMethodServivce.
    - ACTION_PACKAGE_ADDED
    - ACTION_EXTERNAL_APPLICATIONS_AVAILABLE

Basically in the rule A PackageManager gives us the list of relevant
package names that might contain IMEs regardless enabled/disabled
state, and such a list works well to filter out irrelevant
notifications except for one case where a new package is adding one
or new IMEs that we did not know. This is why we also need the rule B.

Even though the rule B requires a secondary query to PackageManager,
it can be done outside of the state lock of IMMS.

 [1]: I7b69c349318ce06a48d03a4468cf2c45bfb73dc2
      c4e44917

Test: Manually verified as follows.
       1. tapas ShortcutDemo && make -j
       2. Copy ShortcutDemo.apk to the current directory.
       3. adb shell dumpsys input_method | grep mMethodMapUpdateCount=
           to check the "mMethodMapUpdateCount".
       4. adb install -r ShortcutDemo.apk
       5. adb shell dumpsys input_method | grep mMethodMapUpdateCount=
           to make sure "mMethodMapUpdateCount" remains unchanged.
       6. adb install -r ShortcutDemo.apk
       7. adb shell dumpsys input_method | grep mMethodMapUpdateCount=
           to make sure "mMethodMapUpdateCount" remains unchanged.
       8. adb uninstall com.example.android.pm.shortcutdemo
       9. adb shell dumpsys input_method | grep mMethodMapUpdateCount=
           to make sure "mMethodMapUpdateCount" remains unchanged.
Test: Manually verified as follows.
       1. tapas SoftKeyboard && make -j
       2. Copy SoftKeyboard.apk to the current directory.
       3. adb root
       4. adb install -r SoftKeyboard.apk
       5. adb shell dumpsys input_method
           Make sure that
             com.example.android.softkeyboard/.SoftKeyboard
           is recognized by IMMS.
       6. adb shell pm disable com.example.android.softkeyboard/.SoftKeyboard
       7. adb shell dumpsys input_method
           Make sure that
             com.example.android.softkeyboard/.SoftKeyboard
           is no longer recognized by IMMS.
       8. adb shell pm enable com.example.android.softkeyboard/.SoftKeyboard
       9. adb shell dumpsys input_method
           Make sure that
             com.example.android.softkeyboard/.SoftKeyboard
           is recognized by IMMS again.
Fixes: 35361128
Change-Id: I063688297156188f68fe0b55a46d72f2e811dc88