Extracted common offer matching functions from SLRP tests.
Extracted common offer matching functions from SLRP tests.

This patch extracts lambda functions `isStoragePool`, `isMountDisk` and
`isPreprovisionedVolume` from all tests and makes them common utitily
functions in the test fixture.

Review: https://reviews.apache.org/r/69904

abudnik/mesos,reneploetz/mesos,dforsyth/mesos,jpeach/mesos,reneploetz/mesos,jpeach/mesos,kaysoky/mesos,kaysoky/mesos,abudnik/mesos,gsantovena/mesos,Gilbert88/mesos,chhsia0/mesos,gsantovena/mesos,abudnik/mesos,dforsyth/mesos,jpeach/mesos,chhsia0/mesos,abudnik/mesos,chhsia0/mesos,reneploetz/mesos,Gilbert88/mesos,jpeach/mesos,chhsia0/mesos,Gilbert88/mesos,dforsyth/mesos,Gilbert88/mesos,gsantovena/mesos,jpeach/mesos,reneploetz/mesos,jpeach/mesos,dforsyth/mesos,gsantovena/mesos,abudnik/mesos,gsantovena/mesos,Gilbert88/mesos,dforsyth/mesos,chhsia0/mesos,kaysoky/mesos,kaysoky/mesos,reneploetz/mesos,dforsyth/mesos,Gilbert88/mesos,jpeach/mesos,reneploetz/mesos,dforsyth/mesos,gsantovena/mesos,abudnik/mesos,Gilbert88/mesos,abudnik/mesos,chhsia0/mesos,kaysoky/mesos,chhsia0/mesos,kaysoky/mesos,gsantovena/mesos,reneploetz/mesos,kaysoky/mesos