fastbootd: Add commands for logical partitions.

This patch adds the following new commands to fastbootd:

    getvar is_logical:<partition>
    create-logical-logical-partition <partition> <size>
    delete-logical-partition <partition>
    resize-logicallogical-partition <partition> <size>

All of these commands operate on logical partitions only, and require a
properly configured "super" partition to operate.

Bug: 78793464
Test: fastboot create-logical-partition example 4096
      fastboot create-logical-partition example 4096 returns error
      fastboot getvar is-logical:example returns "yes"
      fastboot getvar partition-size:example returns "1000"
      fastboot resize-logicalpartition example 8000
      fastboot getvar partition-size:example returns "2000"
      fastboot delete-logical-partition example
      fastboot getvar is-logical:example returns error
      fastboot getvar is-logical:system_a returns "no"

Change-Id: Iff323eabcf5c559fa04c7c92574650b01803eb1f
diff --git a/fastboot/device/variables.h b/fastboot/device/variables.h
index 88947e0..0c706d7 100644
--- a/fastboot/device/variables.h
+++ b/fastboot/device/variables.h
@@ -35,3 +35,4 @@
 bool GetUnlocked(FastbootDevice* device, const std::vector<std::string>& args);
 bool GetHasSlot(FastbootDevice* device, const std::vector<std::string>& args);
 bool GetPartitionSize(FastbootDevice* device, const std::vector<std::string>& args);
+bool GetPartitionIsLogical(FastbootDevice* device, const std::vector<std::string>& args);