fix the SAGA Points Distances tool

[gioman]

Description

1. The "Points Distances" tool had wrong parameters
2. This "Points Distances" tool is the real "Distance Matrix" in SAGA, as no "Distance Matrix" tool exist in SAGA
3. The deleted "Distance Matrix" tool was moreover a copy of the "Minimum Distance Analysis" that does a different thing

Note:

It seems there is a bug the way the SAGA provider outputs to tables:

when the output type is a table and the output is a temp one then it returns always an error like

Cannot open /tmp/processing_15aceb9bb22a4a719ab200d6b673a637/5d7c3d2d4db043259315b26dd65e6748/DISTANCES.shp.()

that ".shp.()" looks suspicious.

Also when electing to save the output to a specific location the default format is SHP (same error as above if chosen) rather than DBF (works ok if chosen).

Checklist

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[stale]

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[stale]

While we hate to see this happen, this PR has been automatically closed because it has not had any activity in the last 21 days. If this pull request should be reconsidered, please follow the guidelines in the previous comment and reopen this pull request. Or, if you have any further questions, just ask! We love to help, and if there's anything the QGIS project can do to help push this PR forward please let us know how we can assist.

[luipir]

as done with other similar PR on SAGA algorithm without tests... I'll merge it. IMHO It's almost safe.

[nyalldawson]

See #8588 for a fix to the dbf issue and a unit test for this alg