dbus-sdr:storagecommands: Add option to use Clear method

There is support in phosphor-sel-logger to clear the SEL files
through its Clear method from,
https://gerrit.openbmc-project.xyz/c/openbmc/phosphor-sel-logger/+/45438
The Clear method API was added through,
https://gerrit.openbmc-project.xyz/c/openbmc/phosphor-dbus-interfaces/+/45402
The packageconfig option is added through,
https://gerrit.openbmc-project.xyz/c/openbmc/openbmc/+/49032

This change will create an option to configure the Clear SEL IPMI
command to call the Clear method, so the Record ID can be restarted
after a clear. If the clears-sel option from phosphor-sel-logger is
used while the IPMI SEL Clear clears the SEL log files, then the
Record ID will not restart at 1.

Tested:
 - Enabled clears-sel in phosphor-sel-logger
 - Enabled sel-logger-clears-sel through packageconfig, and after
   a Clear SEL command, new SEL entries restarted at Record ID 1
   as intended.
 - With sel-logger-clears-sel disabled, the SEL entries continued
   after the latest Record ID before the clear. This indicates that
   the SEL files were cleared by the IPMI Clear SEL command.

Signed-off-by: Charles Boyer <Charles.Boyer@fii-usa.com>
Change-Id: I4461b4ba7449c12e276b1b0e0e7d54ace611643f
2 files changed