bugfix backports

[RonnyPfannschmidt]

• Revert "tmpdir: clean up indirection via config for factories" #6992 by backport #6992 to 5.4.x - restores tmpdir indirection #7066
• running stdlib asyncio unittests again #6927 for pytest 5.4+ doesn't handle IsolatedAsyncioTestCase from CPython core. #6924 by backport #6927: run async testcase methods #7068
• fix #6951: allow to write TerminalReporter.writer #6986 by backport #6986: writable TerminalWriter.writer for deprecation #7067

[RonnyPfannschmidt]

@nicoddemus i hope to get to those either today or tomorrow morning

[nicoddemus]

Awesome, thanks!

[RonnyPfannschmidt]

@nicoddemus i finally had a moment to run trough it, happy easter

[nicoddemus]

Thanks!