Change module and package of Dp, IntPx, etc to unit.

Moved units into ui-unit. Moved some basic utilities
to ui-util. Moved rect, etc into ui-geometry.

This is a start to making proper packages for ui-core classes.

Test: ran tests and connectedCheck
Change-Id: I45fe4a154c0f91cb1526cd73aad6e6e8bed3616a

diff --git a/ui/ui-material/src/androidTest/java/androidx/ui/material/DrawerTest.kt b/ui/ui-material/src/androidTest/java/androidx/ui/material/DrawerTest.kt
index 3f915b8..4f9080f 100644
--- a/ui/ui-material/src/androidTest/java/androidx/ui/material/DrawerTest.kt
+++ b/ui/ui-material/src/androidTest/java/androidx/ui/material/DrawerTest.kt

@@ -19,17 +19,17 @@
 import androidx.compose.Model
 import androidx.test.filters.MediumTest
 import androidx.ui.core.OnPositioned
-import androidx.ui.core.PxPosition
-import androidx.ui.core.PxSize
 import androidx.ui.core.TestTag
-import androidx.ui.core.dp
-import androidx.ui.core.round
 import androidx.ui.foundation.Clickable
 import androidx.ui.layout.Container
 import androidx.ui.semantics.Semantics
 import androidx.ui.test.createComposeRule
 import androidx.ui.test.doClick
 import androidx.ui.test.findByTag
+import androidx.ui.unit.PxPosition
+import androidx.ui.unit.PxSize
+import androidx.ui.unit.dp
+import androidx.ui.unit.round
 import com.google.common.truth.Truth.assertThat
 import org.junit.Ignore
 import org.junit.Rule