Refactor Storage Provider to FSM Module

[hannahhoward]

Goals

Convert the storage provider to the FSM module, add many unit tests, generally refactor to make code more manageable and legible

Implementation

• Refactor all provider states to the FSM module
• Factor our some common utility functions
• Factor out storage ask code from storage provider -- this is a fairly discreet unity of functionality which makes the storage provider code much larger
• Factor out common code on client & provider used to manage connections
• Add unit tests to: new provider FSM code, utility functions, factored out modules

[codecov-io]

Codecov Report

Merging #145 into master will increase coverage by 3.21%.
The diff coverage is 93.4%.

@@            Coverage Diff             @@
##           master     #145      +/-   ##
==========================================
+ Coverage   78.86%   82.07%   +3.21%     
==========================================
  Files          27       33       +6     
  Lines        1225     1561     +336     
==========================================
+ Hits          966     1281     +315     
- Misses        189      200      +11     
- Partials       70       80      +10

Impacted Files	Coverage Δ
storagemarket/types.go	100% <ø> (ø)	⬆️
storagemarket/impl/clientutils/clientutils.go	100% <ø> (ø)
storagemarket/impl/clientstates/client_fsm.go	100% <ø> (ø)	⬆️
storagemarket/impl/providerstates/provider_fsm.go	100% <100%> (ø)
storagemarket/impl/connmanager/connmanager.go	100% <100%> (ø)
storagemarket/impl/storedask/storedask.go	81.43% <81.43%> (ø)
storagemarket/impl/providerutils/providerutils.go	88.24% <88.24%> (ø)
...oragemarket/impl/providerstates/provider_states.go	97.13% <97.13%> (ø)
... and 4 more

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[ingar]

Looks good.

One minor point: was a little confused by the use of the storagemarket.StorageDealProposalAccepted state. On the provider, it's used to indicate sort of a "conditional acceptance", pending data transfer and validation and funds. On the Client it means something different (staged I think). Not a huge deal, but it could be confusing if you just looked at the existing deal states without looking through the FSM.

[hannahhoward]

@ingar -- my next step is to finally do that conditional acceptance ticket (where the provider sends conditional accepts and the client creates the data transfer)