Add fibre channel support

[peter-wangxu]

• ConnectVolume for fc protocol.
• Efficient fc host rescan instead of wildcard rescan.

[codecov]

Codecov Report

Merging #18 into master will decrease coverage by 3.11%.
The diff coverage is 83.43%.

@@            Coverage Diff            @@
##           master     #18      +/-   ##
=========================================
- Coverage   82.32%   79.2%   -3.12%     
=========================================
  Files          12      14       +2     
  Lines         826    1082     +256     
=========================================
+ Hits          680     857     +177     
- Misses        122     193      +71     
- Partials       24      32       +8

Impacted Files	Coverage Δ
client/iscsi.go	100% <100%> (ø)	⬆️
linux/fc.go	90.32% <100%> (-0.31%)	⬇️
linux/scsi.go	91.54% <100%> (-2.13%)	⬇️
cmd/app.go	100% <100%> (ø)	⬆️
client/base.go	76.13% <70.76%> (-15.17%)	⬇️
util/common.go	37.25% <80%> (ø)
connector/fibre_channel.go	80.3% <80.3%> (ø)
connector/iscsi.go	80.3% <85.71%> (-0.11%)	⬇️
connector/base.go	84.31% <87.23%> (+17.64%)	⬆️
model/model.go	82.48% <87.69%> (+0.09%)	⬆️
... and 4 more

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