Added chatbot and chatbot standalone descriptions for bot versions #1,#2

When botversion #1 is registered, chatbot version 1.0 description is set.
When botversions #1, #2 is registered, chatbot version 1.0 and 2.0 descriptions are set.

Bug: b/213487716
Test: atest PublishServiceDescTrackerTest
Change-Id: I0b2d85f4230844b30eb67178647829b12ba932bb
Merged-In: I0b2d85f4230844b30eb67178647829b12ba932bb