remote/client: support token with template RemotePlace

[nlabriet]

Description
Using a template for RemotePlace is very useful to avoid repetition.
This change adds support for token, when LG_PLACE == + or +TOKEN.

      RemotePlace:
        name: !template $LG_PLACE

The role containing the !template $LG_PLACE will be used if no other match is found.

It's a first step, one can imagine supporting more complex patterns like (see #1194):

      RemotePlace:
        name: !template "$LG_PLACE-bbb"

Checklist

• Documentation for the feature
• Tests for the feature
• test added in tests/test_crossbar.py
• PR has been tested
• I tested local with the setup described in Structuring multiple boards in environment config #1194

Partially fixes #1194

[codecov]

Codecov Report

Patch coverage: 100.0% and project coverage change: +0.3 🎉

Comparison is base (acd4d43) 63.0% compared to head (d2f8e83) 63.3%.

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #1208     +/-   ##
========================================
+ Coverage    63.0%   63.3%   +0.3%     
========================================
  Files         159     159             
  Lines       11683   11686      +3     
========================================
+ Hits         7365    7405     +40     
+ Misses       4318    4281     -37     

Impacted Files	Coverage Δ
labgrid/remote/client.py	54.1% <100.0%> (+2.7%)	⬆️

... and 2 files with indirect coverage changes

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