Support WMTS Dimensions

[Don-vip]

From #14824:

Add a new layer from ​http://wmts.geo.admin.ch/1.0.0/WMTSCapabilities.xml

The URL uses Time dimension:

<Layer>
  <ows:Title>Agglomeration and isolated cities</ows:Title>
  <ows:Abstract>
The agglomerations and isolated cities (municipalities with at least 10,000 residents which do not form part of an agglomeration) are among the regions used for analysis in Swiss statistics. This geographical category has existed for more than one hundred years. Its purpose is to measure urbanisation as a fundamental phenomenon of spatial organisation, in order to allow a spatial comparison to be made between urban areas that have been differently defined from an institutional perspective. A previous version was first used in 1930 and this was then revised in 1984 and 1990, each time on the basis of data from population censuses. The current version classifies the 2,896 municipalities in Switzerland (data from 2000) as belonging or not belonging to the category of agglomeration or isolated city on the basis of statistical criteria (level and growth of the population; structural context; the ratio of employed people to residents; the economic structure; the commuter flows). The agglomerations and isolated cities make up the urban space. The Federal Statistical Office (FSO) definition of agglomerations is not legally binding.
  </ows:Abstract>
  <ows:WGS84BoundingBox>
    <ows:LowerCorner>5.140242 45.398181</ows:LowerCorner>
    <ows:UpperCorner>11.47757 48.230651</ows:UpperCorner>
  </ows:WGS84BoundingBox>
  <ows:Identifier>ch.are.agglomerationen_isolierte_staedte</ows:Identifier>
  <ows:Metadata xlink:href="http://www.geocat.ch/geonetwork/srv/deu/metadata.show?uuid=c1a563a5-3af3-4fd6-b2fd-1e4b010f0fc4"/>
  <Style>
    <ows:Title>Agglomeration and isolated cities</ows:Title>
    <ows:Identifier>ch.are.agglomerationen_isolierte_staedte</ows:Identifier>
    <LegendURL format="image/png" xlink:href="http://api3.geo.admin.ch/static/images/legends/ch.are.agglomerationen_isolierte_staedte_en.png"/>
  </Style>
  <Format>image/png</Format>
  <Dimension>
    <ows:Identifier>Time</ows:Identifier>
    <Default>20140101</Default>
    <Value>20140101</Value>
  </Dimension>
  <TileMatrixSetLink>
    <TileMatrixSet>21781_26</TileMatrixSet>
  </TileMatrixSetLink>
  <ResourceURL format="image/png" resourceType="tile" template="http://wmts.geo.admin.ch/1.0.0/ch.are.agglomerationen_isolierte_staedte/default/{Time}/21781/{TileMatrix}/{TileRow}/{TileCol}.png"/>
</Layer>

We must parse this information and replace the dimensions in the URL template by the default value.

[Don-vip]

In 12224/josm:

fix #14825 - Support WMTS Dimensions