stored: fix crashes of storage tools when autoxflate plugin is loaded

[pstorz]

The low level storage tools bcopy, bextract, bls, bscan and btape load sd plugins if they are configured.

Unfortunately, the plugin event bSdEventSetupRecordTranslation was not emitted before, so that the autoxflate plugin did not setup the compression buffers.

Now, all these tools do emit the plugin event, and the autoxflate-sd plugin also checks for the buffer before using it and emits an message otherwise.

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[arogge]

AFAIR we have autoxflate in the "basic" bareos test.
We should add more sub-tests that run the tools (at least bextract, bls and bscan) on the volumes created by the basic backup/restore test.

[arogge]

The tests look promising, but apparently we have memory leaks in the tools when autoxflate is enabled, thus the tests fail in the sanitizer stage.
I think there is also a fixture missing, as with enough parallelism (i.e. -j 100) the tests failed on my machine, too.