Ruby-client: Don't encode slashes if strict-spec false (#3204)

URL-special characters such as /,?,% should be encoded when inside path
parameters. I changed the Ruby-client to do so.
OpenAPITools/openapi-generator#3039

Unfortunately, some projects relied on slashes not being expanded within
path paramters:
OpenAPITools/openapi-generator#3119

With this commit, these projects can now pass `--strict-spec false` to
not have / converted to %2F.

strict spec not specified: / -> %2F
--strict-spec true: / -> %2F
--strict-spec false: / -> /

Author: ccouzens

.generator/templates/api.mustache

@@ -123,7 +123,7 @@ module {{moduleName}}
       {{/hasValidation}}
       {{/allParams}}
       # resource path
-      local_var_path = '{{{path}}}'{{#pathParams}}.sub('{' + '{{baseName}}' + '}', CGI.escape({{paramName}}.to_s)){{/pathParams}}
+      local_var_path = '{{{path}}}'{{#pathParams}}.sub('{' + '{{baseName}}' + '}', CGI.escape({{paramName}}.to_s){{^strictSpecBehavior}}.gsub('%2F', '/'){{/strictSpecBehavior}}){{/pathParams}}
 
       # query parameters
       query_params = opts[:query_params] || {}