changed search submit value for Accessibility
Change "Search Packages" to simple "Submit"
Added p0 tests for read-only mode
Updating vsmdi
Added ReadOnlyModeTests to bsmdi
Merge pull request #2131 from robertmuehsig/1187-searchboxsubmit

'Search Packages' for Search Button for Accessibility  #1187
Merge pull request #2147 from NuGet/bhuvak-readonlymodetests

Added p0 tests for read-only mode