ERP5: generate an interpreter for theia

Set in preferences the path of this interpreter, for example:

```json
{
  "python.pythonPath": "/srv/slapgrid/slappart19/srv/runner/software/91be79296dea036ad98d4aff08ecb74b/bin/python"
}
```

then when editing products files completions and jump to definition should work. It works but it is sometimes so slow that it seems not working.

See merge request nexedi/slapos!1153

stack/erp5/buildout.cfg

@@ -58,6 +58,7 @@ extends =
   ../../component/perl-Image-ExifTool/buildout.cfg
   ../../component/wendelin.core/buildout.cfg
   ../../component/jupyter-py2/buildout.cfg
+  ../../component/pygolang/buildout.cfg
   ../../stack/caucase/buildout.cfg
   ../../software/neoppod/software-common.cfg
 # keep neoppod extends last
@@ -72,7 +73,7 @@ parts +=
 # Buildoutish
   eggs-all-scripts
   testrunner
-  test_suite_runner
+  test-suite-runner
 
 # get git repositories
   genbt5list
@@ -204,7 +205,7 @@ context =
     key site_zcml site-zcml:target
     key sixtunnel_location 6tunnel:location
     key template_run_zelenium template-run-zelenium:target
-    key egg_interpreter eggs:interpreter
+    key egg_interpreter erp5-python-interpreter:interpreter
     key template_apache_conf template-apache-backend-conf:target
     key template_balancer template-balancer:target
     key template_erp5 template-erp5:target
@@ -368,7 +369,7 @@ initialization =
     for x in os.getenv('INSERT_PRODUCTS_PATH', '').split(os.pathsep)), [])
   os.environ['PATH'] = '${jsl:location}/bin:%s' % os.environ['PATH']
 
-[test_suite_runner]
+[test-suite-runner]
 # XXX: Workaround for fact ERP5Type is not an distribution and does not
 #      expose entry point for test runner
 recipe = zc.recipe.egg
@@ -386,6 +387,13 @@ initialization =
   repository_id_list = list(reversed('''${erp5_repository_list:repository_id_list}'''.split()))
   sys.path[0:0] = ['/'.join(['''${buildout:parts-directory}''', x]) for x in repository_id_list]
 
+[erp5-python-interpreter]
+<= python-interpreter
+# a python interpreter with all eggs available, usable for the software release but also
+# for external tools (such as python extension in theia).
+eggs += ${eggs:eggs}
+extra-paths += ${eggs:extra-paths}
+
 [zope-product-with-eggtestinfo]
 recipe = zc.recipe.egg:custom
 setup-eggs =
@@ -560,10 +568,6 @@ eggs = ${neoppod:eggs}
   strict-rfc3339
   jsonschema[format]
 
-# parameterizing the version of the generated python interpreter name by the
-# python section version causes dependency between this egg section and the
-# installation of python, which we don't want on an instance
-interpreter = ${buildout:python}
 entry-points =
   runwsgi=Products.ERP5.bin.zopewsgi:runwsgi
 scripts =