Clean up SearchableInfo API, JavaDoc and formatting

This change cleans up the JavaDoc in SearchableInfo,
removes trailing whitespace, fixes an if-statement
style violoation, and re-hides some things that were
exposed for Froyo that query deprecated or discouraged
attributes:

SearchableInfo.getSearchButtonText()
SearchableInfo.getLabelId()
SearchableInfo.getIconlId()
class SearchableInfo.ActionKeyInfo
SearchableInfo.findActionKey()

Bug http://b/issue?id=2553524

Change-Id: Iee5521c844f74137166730e523d29ba07ef1856b