main: catch exceptions when loading blob handlers
main: catch exceptions when loading blob handlers

If an error occurs while attempting to load the blob handlers (such as a
filesystem error), the uncaught exception will crash the entire IPMI
daemon. Instead, catch the exception and print an error message.

Tested: ipmid doesn't crash when /usr/lib/blobs-ipmid is missing
Signed-off-by: Benjamin Fair <57b1bdb8e1cf9c64770707a0983e9d8ca40b3405@google.com>
Change-Id: Ic316f6e5aa3c4bc6eba4fa2e561b338f4b20f606

openbmc/phosphor-ipmi-blobs