WL#9541 : Move MTR documentation to Doxygen

Move MTR documentation from current infrastructure to Doxygen.

- Added a new section in TOC of existing MySQL source code
  documentation main page. New section added has a subsection
  called "The MySQL Test Framework, Version 2.0" which contains
  MTR documentation.

- mysql-test/mysql-test-run.dox, MTR documentation file.

Reviewed-by: Anitha Gopi <[email protected]
Reviewed-by: Georgi Kodinov <[email protected]>
Reviewed-by: Marc Alff <[email protected]>
RB: 15460

Author: Pavan Naik

Doxyfile

@@ -855,6 +855,7 @@ INPUT                  = ./client \
                          ./libbinlogevents \
                          ./libbinlogstandalone \
                          ./libservices \
+                         ./mysql-test/mysql-test-run.dox \
                          ./mysys \
                          ./mysys_ssl \
                          ./plugin/audit_null \
@@ -941,7 +942,6 @@ EXCLUDE                = cmd-line-utils \
                          libevent \
                          libmysql \
                          libmysql_r \
-                         mysql-test \
                          plugin/innodb_memcached/daemon_memcached/include/memcached \
                          source_downloads \
                          sql/sql_hints.cc \