Change MeteredDataDisabled function names for clarity

Add the word Packages to several functions to clarify Metered Data is
disabled on a per Package basis.

setMeteredDataDisabled to setMeteredDataDisabledPackages
getMeteredDataDisabled to getMeteredDataDisabledPackages
isMeteredDataDisabledForUser to isMeteredDataDisabledForUserPackage

Change-Id: Ied755b4422f8689e34bdb68d733d60fbfc47c692
Fixes: 73803958
Test: cts-tradefed run singleCommand cts-dev -m CtsDevicePolicyManagerTestCases -t com.android.cts.devicepolicy.MixedDeviceOwnerTest#testSetMeteredDataDisabledPackages
Test: cts-tradefed run singleCommand cts-dev -m CtsDevicePolicyManagerTestCases -t com.android.cts.devicepolicy.MixedProfileOwnerTest#testSetMeteredDataDisabledPackages
Test: atest com.android.server.devicepolicy.DevicePolicyManagerTest#testSetGetMeteredDataDisabledPackages