Add clear session button to Request panel #685

Job	Run time
testsuite / testsuite-linux (8.2, pgsql, highest, false)	42s
testsuite / testsuite-linux (8.3, sqlite, highest, false)	33s
testsuite / testsuite-linux (8.2, mysql, highest, false)	59s
testsuite / testsuite-linux (8.5, sqlite, highest, false)	35s
testsuite / testsuite-linux (8.4, mysql, highest, false)	48s
testsuite / testsuite-linux (8.2, sqlite, lowest, false)	31s
cs-stan / Coding Standard & Static Analysis	43s
	4m 51s

Provide feedback