Embedded-storage by using torrentfs

[ucwong]

embedded storage to cortex full node and make the fast mode available

[codecov]

Codecov Report

Merging #690 into master will decrease coverage by 0.04%.
The diff coverage is 3.12%.

@@            Coverage Diff             @@
##           master     #690      +/-   ##
==========================================
- Coverage   50.67%   50.63%   -0.05%     
==========================================
  Files         414      414              
  Lines       52163    52198      +35     
==========================================
- Hits        26433    26428       -5     
- Misses      23696    23737      +41     
+ Partials     2034     2033       -1     

Impacted Files	Coverage Δ
cmd/cortex/config.go	0.00% <0.00%> (ø)
cmd/cortex/cvm.go	2.77% <0.00%> (ø)
cmd/utils/flags.go	2.10% <0.00%> (-0.01%)	⬇️
core/vm/cvm.go	15.67% <0.00%> (+0.05%)	⬆️
core/vm/interpreter.go	27.58% <0.00%> (-0.56%)	⬇️
inference/synapse/local_infer.go	0.00% <0.00%> (ø)
inference/synapse/synapse.go	0.00% <0.00%> (ø)
core/state_transition.go	45.56% <3.84%> (-4.44%)	⬇️
ctxc/handler.go	43.11% <33.33%> (+0.34%)	⬆️
consensus/cuckoo/sealer.go	0.00% <0.00%> (-6.76%)	⬇️
... and 16 more