Adapt capacity tags for camp sites etc. (#107)

* Add capacity:* tags for tourism=camp_site.

* Use capacity:caravans for tourism=caravan_site.

* Use distinct capacity tags for tourism=camp_site.

* upgrade capacity fields to regular fields


Co-authored-by: Martin Raifer <martin@raifer.tech>

data/fields/capacity/caravans.json

@@ -0,0 +1,7 @@
+{
+    "key": "capacity:caravans",
+    "type": "number",
+    "minValue": 0,
+    "label": "Capacity (Caravans)",
+    "placeholder": "10, 20, 50..."
+}

data/fields/capacity/persons.json

@@ -0,0 +1,7 @@
+{
+    "key": "capacity:persons",
+    "type": "number",
+    "minValue": 0,
+    "label": "Capacity (Persons)",
+    "placeholder": "50, 100, 200..."
+}

data/fields/capacity/tents.json

@@ -0,0 +1,11 @@
+{
+    "key": "capacity:tents",
+    "type": "number",
+    "minValue": 0,
+    "label": "Capacity (Tents)",
+    "placeholder": "10, 20, 50...",
+    "prerequisiteTag": {
+        "key": "tents",
+        "valueNot": "no"
+    }
+}