Create service descriptor for hoverdrive endpoints

Hoverdrive provides two endpoints for getting documentation links about
tables and columns respectively. These endpoints are described in
https://sqr-086.lsst.io.

Both endpoints provide an optional mode triggered by a ?redirect=true
query parameter where the client is redirected to the most-relevant
documentation URL. In this case, only a single column or table can be
specified by the ?table and ?column parameters. I'm not sure how to
encode this logic in the service descriptor.

Author: jonathansick

datalink/hoverdrive.xml

@@ -0,0 +1,54 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<VOTABLE xmlns="http://www.ivoa.net/xml/VOTable/v1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2">
+
+  <RESOURCE type="meta" utype="adhoc:service" name="ColumnDocumentationLinks">
+    <DESCRIPTION>
+      Get documentation links about table columns.
+    </DESCRIPTION>
+    <PARAM name="accessURL" datatype="char" arraysize="*"
+          value="$baseUrl$/api/hoverdrive/column-docs-links"/>
+    <GROUP name="inputParams">
+      <PARAM name="table" datatype="char" use="required">
+        <DESCRIPTION>The name of the table.</DESCRIPTION>
+      </PARAM>
+      <PARAM name="column" datatype="char" arraysize="*" use="required">
+        <DESCRIPTION>The name of the column.</DESCRIPTION>
+      </PARAM>
+      <PARAM name="redirect" datatype="boolean" value="False" use="optional">
+        <DESCRIPTION>Whether to redirect to the most relevant documentation link.</DESCRIPTION>
+      </PARAM>
+    </GROUP>
+    <PARAM name="exampleURL" datatype="char" arraysize="*"
+          value="$baseUrl$/api/hoverdrive/column-docs-links?table=dp02_dc2_catalogs.Object&amp;column=detect_isPrimary&amp;redirect=true">
+      <DESCRIPTION>Example request to redirect to the documentation for the 'detect_isPrimary' column in the 'dp02_dc2_catalogs.Object' table.</DESCRIPTION>
+    </PARAM>
+    <PARAM name="exampleURL" datatype="char" arraysize="*"
+          value="$baseUrl$/api/hoverdrive/column-docs-links?table=dp02_dc2_catalogs.Object&amp;column=ra&amp;column=dec">
+      <DESCRIPTION>Example request to get (but not redirect to) documentation links for the 'ra' and 'dec' columns in the 'dp02_dc2_catalogs.Object' table (redirect=false is the default).</DESCRIPTION>
+    </PARAM>
+  </RESOURCE>
+
+  <RESOURCE type="meta" utype="adhoc:service" name="TableDocumentationLinks">
+    <DESCRIPTION>
+      Get documentation links about tables.
+    </DESCRIPTION>
+    <PARAM name="accessURL" datatype="char" arraysize="*"
+          value="$baseUrl$/api/hoverdrive/table-docs-links"/>
+    <GROUP name="inputParams">
+      <PARAM name="table" datatype="char" arraysize="*" use="required">
+        <DESCRIPTION>The name of the table.</DESCRIPTION>
+      </PARAM>
+      <PARAM name="redirect" datatype="boolean" value="False" use="optional">
+        <DESCRIPTION>Whether to redirect to the most relevant documentation link.</DESCRIPTION>
+      </PARAM>
+    </GROUP>
+    <PARAM name="exampleURL" datatype="char" arraysize="*"
+          value="$baseUrl$/api/hoverdrive/table-docs-links?table=dp02_dc2_catalogs.Object&amp;redirect=true">
+      <DESCRIPTION>Example request to redirect to the documentation for the 'dp02_dc2_catalogs.Object' table.</DESCRIPTION>
+    </PARAM>
+    <PARAM name="exampleURL" datatype="char" arraysize="*"
+          value="$baseUrl$/api/hoverdrive/table-docs-links?table=dp02_dc2_catalogs.Object">
+      <DESCRIPTION>Example request to get (but not redirect to) the documentation link for the 'dp02_dc2_catalogs.Object' table (redirect=false is the default).</DESCRIPTION>
+    </PARAM>
+  </RESOURCE>
+</VOTABLE>

docs/changes/DM-50405.misc.md

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+Added service descriptors for Hoverdrive endpoints.