Improve debuggability by adding option to not remove temporary openssl config files

[Yannik]

In #596 (comment), I suggested adding an option to not remove the temporary openssl config/extfile to improve debuggability.

Currently, this can only be achieved by commenting out

[ -z "$EASYRSA_TEMP_DIR_session" ] || rm -rf "$EASYRSA_TEMP_DIR_session"

and

rm -f "$easyrsa_openssl_conf"
rm -f "$easyrsa_extra_exts"

[TinCanTech]

This is already taken care of.

easy-rsa/easyrsa3/easyrsa

Lines 656 to 662 in e5ec1ab

	# Make a copy safe SSL config file for comparison (undocumented)
	make_safe_ssl_copy() {
	no_pki_required=1
	require_safe_ssl_conf=1
	make_copy_ssl_conf=1
	easyrsa_openssl makesafeconf
	} # => make_safe_ssl_copy()

[TinCanTech]

This is not a complete solution.

There is no other way to do this, other than to keep the temporary config file for verification.

Example: This string is not expanded by easyrsa, x509-types/kdc:

• ${ENV::EASYRSA_KDC_REALM}

[TinCanTech]

Testing welcome. #667