Adds check to see if storage nodes are eligible to initiate
graceful exit, by checking their CreatedAt date and seeing if
their "age" is greater than the new config value:
NodeMinAgeInMonths
The default for this value is 6 months for now.
https://storjlabs.atlassian.net/browse/V3-3357
Change-Id: Ib807ab8987ddb5a38a27a83886490f73fe8c5816
* add overall failure percentage check and inactive time frame check before sending a response to sno
* update comment
* delete node from transfer queue if it has been inactive for too long
* fix linting error
* add test config value
* fix nil pointer
* add config value into testplanet
* add unit test for overall failure threshold
* move timeframe threshold to chore
* update protolock
* add chore test
* add per peiece failure count logic
* change config name from EndpointMaxFailures to MaxFailuresPerPiece
* address comments
* fix linting error
* add error handling for no row returned from progress table
* fix test for graceful exit chore on storagenode
* fix typo InActive -> Inactive
* improve readability for failure threshold calculation
* update config lock
* change error handling for GetProgress in graceful exit endpoint on the satellite side
* return proper rpc error in endpoint
* add check in chore test for checking finish timestamp and queue
* update lock file and add comment
* add created at and bytes transferred
* cleanup
* rename db func to GetGracefulExitNodesByTimeFrame
* fix flag
* split into two overlay functions
* := to =
* fix test
* add node not found error class
* fix overlay test
* suggested test changes
* review suggestions
* get exit status from overlay.Get()
* check rows.Err
* fix panic when ExitFinishedAt is nil
* fix comments in cmdGracefulExit
