Documentation: KUnit: remove duplicated docs for kunit_tool

Documentation: KUnit: remove duplicated docs for kunit_tool

Delete "kunit-tool.rst" to remove repeated info from KUnit docs.
"What is kunit_tool?" was integrated into index.rst, the remaining
sections were moved into run_wrapper.rst and renamed as follows:

"What is a .kunitconfig?" -> "Creating a ``.kunitconfig`` file"
"Getting Started with kunit_tool" -> "Running tests with kunit_tool"
"Configuring, Building, and Running Tests" ->
	"Configuring, building, and running tests"
"Running Tests on QEMU" -> "Running tests on QEMU"
"Parsing Test Results" -> "Parsing test results"
"Filtering Tests" -> "Filtering tests"
"Other Useful Options" -> "Running command-line arguments"

Signed-off-by: Tales Aparecida <tales.aparecida@gmail.com>
Reviewed-by: Sadiya Kazi <sadiyakazi@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>