This is the implementation of the new DB connections API (grant proposal 2019).
Summary
The new API makes it available to QGIS core a new interface for provider connections and will allow to:
replace the provider specific QgsSettings management in QGIS4 (save/load connections from the settings) NOT IN SCOPE FOR NOW.
provide a unified API for common operations on DB connections:
executeSql and get the results
list tables names and properties and schemas
create a new vector table (no rasters for now)
create/rename/drop schemas and tables
vacuum
....
* Remove deprecated Qgis::WKBType and API cleanup
Renames QgsWKBTypes to QgsWkbTypes
Replaces usage of the enums:
* Qgis::WKBType with QgsWkbTypes::Type
* Qgis::GeometryType with QgsWkbTypes::GeometryType
Their values should be forward compatible (a fact that was already
explited up to now by casting between the types)
Renames some SSLxxx to SslXxx and URIxxx to UriXxx
* Fix build warnings and simplify type handling
* Add a fixer to rewrite imports
* The forgotten rebase conflictThe forgotten rebase conflicts
* QgsDataSourcURI > QgsDataSourceUri
* QgsWKBTypes > QgsWkbTypes
* Qgis.WKBGeom > QgsWkbTypes.Geom
* Further python fixes
* Guess what... Qgis::wkbDimensions != QgsWkbTypes::wkbDimensions
* Fix tests
* Python 3 updates
* [travis] pull request caching cannot be disabled
so at least use it in r/w mode
* Fix python3 print in plugins
