Add platform/tools/dexter to manifest.

It is checked out at tools/dexter.

Test: repo sync
Bug: 65011851
Change-Id: I9ea14b5fba45b53636f3392cd1e04269231278e9

default.xml

@@ -605,6 +605,7 @@
   <project path="tools/apksig" name="platform/tools/apksig" groups="pdk,tradefed" />
   <project path="tools/base" name="platform/tools/base" groups="notdefault,tools" />
   <project path="tools/build" name="platform/tools/build" groups="notdefault,tools" />
+  <project path="tools/dexter" name="platform/tools/dexter" groups="tools" />
   <project path="tools/external/fat32lib" name="platform/tools/external/fat32lib" groups="tools" />
   <project path="tools/external/gradle" name="platform/tools/external/gradle" groups="tools" />
   <project path="tools/idea" name="platform/tools/idea" groups="notdefault,tools" />