scripts/resulttool: group all regressions in regression report

scripts/resulttool: group all regressions in regression report

Commit c304fcbe0588b1078373558c2ddf36064bcdf214 introduced a grouping when
listing regressions. This grouping has been added only for ptests. It has
been observed that any other kind of tests could benefit from it. For
example, current regression reports can show the following:

1 regression(s) for oescripts.OEGitproxyTests.test_oegitproxy_proxy_dash
    oescripts.OEGitproxyTests.test_oegitproxy_proxy_dash: PASSED -> SKIPPED
1 regression(s) for oescripts.OEPybootchartguyTests.test_pybootchartguy_help
    oescripts.OEPybootchartguyTests.test_pybootchartguy_help: PASSED -> SKIPPED
1 regression(s) for oescripts.OEPybootchartguyTests.test_pybootchartguy_to_generate_build_pdf_output
    oescripts.OEPybootchartguyTests.test_pybootchartguy_to_generate_build_pdf_output: PASSED -> SKIPPED
1 regression(s) for oescripts.OEPybootchartguyTests.test_pybootchartguy_to_generate_build_png_output
    oescripts.OEPybootchartguyTests.test_pybootchartguy_to_generate_build_png_output: PASSED -> SKIPPED
1 regression(s) for oescripts.OEPybootchartguyTests.test_pybootchartguy_to_generate_build_svg_output
    oescripts.OEPybootchartguyTests.test_pybootchartguy_to_generate_build_svg_output: PASSED -> SKIPPED
[...]

This output is not so useful in its current state and should be grouped per
test type too.
Enable grouping for all kind of tests, to make it llok like the following
in reports:
5 regression(s) for oescripts
    oescripts.OEGitproxyTests.test_oegitproxy_proxy_dash: PASSED -> SKIPPED
    oescripts.OEPybootchartguyTests.test_pybootchartguy_help: PASSED -> SKIPPED
    oescripts.OEPybootchartguyTests.test_pybootchartguy_to_generate_build_pdf_output: PASSED -> SKIPPED
    oescripts.OEPybootchartguyTests.test_pybootchartguy_to_generate_build_png_output: PASSED -> SKIPPED
    oescripts.OEPybootchartguyTests.test_pybootchartguy_to_generate_build_svg_output: PASSED -> SKIPPED

Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>