Improve LockService functionality and flexibility

[nvoxland]

Implementation of #1453

[fbiville]

it might be worthwhile switching to Duration types instead of numeric types for wait and recheck times.

[nvoxland]

Realized an issue with the heartbeat strategy: Liquibase currently makes just one connection but the heartbeat thread needs a separate connection for transaction reasons. We can't have the heartbeat committing the normal liquibase transaction, and we can't have it waiting for a commit from the normal connection.

We'll have to build in support for opening separate connections before we can make progress on this.

[codecov]

Codecov Report

Merging #1541 (0eb8df0) into master (43ed0e5) will increase coverage by 1.59%.
The diff coverage is 41.43%.

@@             Coverage Diff              @@
##             master    #1541      +/-   ##
============================================
+ Coverage     48.01%   49.60%   +1.59%     
+ Complexity     7903     7867      -36     
============================================
  Files           793      757      -36     
  Lines         38608    37042    -1566     
  Branches       6904     6703     -201     
============================================
- Hits          18536    18374     -162     
+ Misses        17645    16236    -1409     
- Partials       2427     2432       +5     

Impacted Files	Coverage Δ	Complexity Δ
...uibase-core/src/main/java/liquibase/Liquibase.java	39.88% <ø> (-1.79%)	57.00 <0.00> (-5.00)
...a/liquibase/change/core/CreateProcedureChange.java	29.16% <0.00%> (+0.24%)	24.00 <0.00> (ø)
...va/liquibase/change/core/LoadUpdateDataChange.java	27.27% <ø> (+2.27%)	9.00 <0.00> (+1.00)
...liquibase/command/core/DiffToChangeLogCommand.java	7.40% <0.00%> (+0.26%)	2.00 <0.00> (ø)
...n/java/liquibase/command/core/SnapshotCommand.java	3.77% <ø> (+0.06%)	2.00 <0.00> (ø)
...in/java/liquibase/database/core/MySQLDatabase.java	32.03% <0.00%> (+2.87%)	28.00 <0.00> (ø)
...java/liquibase/database/core/PostgresDatabase.java	44.68% <0.00%> (+0.70%)	37.00 <0.00> (+1.00)
...quibase/diff/output/changelog/DiffToChangeLog.java	34.12% <0.00%> (-0.69%)	31.00 <0.00> (ø)
...e/src/main/java/liquibase/hub/core/HttpClient.java	15.09% <0.00%> (-0.30%)	5.00 <0.00> (ø)
...main/java/liquibase/hub/core/OnlineHubService.java	27.30% <0.00%> (-0.31%)	18.00 <0.00> (ø)
... and 189 more

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