Support catchment {{id}} substitution in init_config field of global single module formulations

[aaraney]

{{id}} is not substituted with the modeled catchment id in global single module formulations (e.g. init_config: "some_config_{{id}}.format") like they are in a multi-bmi formulation. It is desirable that this behavior is replicated in the single module formulation variant.

Substitution occurs in the multi-bmi case here:

ngen/include/realizations/catchment/Bmi_Multi_Formulation.hpp

Lines 640 to 642 in 0917f9b

	// Since this is a nested formulation, support usage of the '{{id}}' syntax for init config file paths.
	Catchment_Formulation::config_pattern_substitution(properties, BMI_REALIZATION_CFG_PARAM_REQ__INIT_CONFIG,
	"{{id}}", id);

Example:

{
    "global": {
      "formulations": [
        {
          "name": "bmi_c++",
          "params": {
            "model_type_name": "test_bmi_cpp",
            "library_file": "./extern/test_bmi_cpp/cmake_build/libtestbmicppmodel",
            "init_config": "./data/bmi/c/test/test_bmi_c_config_{{id}}.ini",
            "main_output_variable": "OUTPUT_VAR_2",
            "variables_names_map" : {
              "INPUT_VAR_2": "TMP_2maboveground",
              "INPUT_VAR_1": "precip_rate"
            },
            "uses_forcing_file": false
          }
        }
      ],
      "forcing": {
          "file_pattern": ".*{{id}}.*.csv",
          "path": "./data/forcing/"
      }
    },
    "time": {
        "start_time": "2015-12-01 00:00:00",
        "end_time": "2015-12-30 23:00:00",
        "output_interval": 3600
    }
}

This will throw the following error:

Cannot create and initialize libtestbmicppmodel using unreadable file './data/bmi/c/test/test_bmi_c_config_{{id}}.ini'. Error: No such file or directory

Current workaround:

Wrap the single module in a multi-bmi formulation.

Example

{
  "global": {
    "formulations": [
      {
        "name": "bmi_multi",
        "params": {
          "model_type_name": "work_around",
          "forcing_file": "",
          "init_config": "",
          "allow_exceed_end_time": true,
          "main_output_variable": "OUTPUT_VAR_2",
          "uses_forcing_file": false,
          "modules": [
            {
              "name": "bmi_c++",
              "params": {
                "model_type_name": "test_bmi_cpp",
                "library_file": "./extern/test_bmi_cpp/cmake_build/libtestbmicppmodel",
                "init_config": "./data/bmi/c/test/test_bmi_c_config_{{id}}.ini",
                "main_output_variable": "OUTPUT_VAR_2",
                "variables_names_map": {
                  "INPUT_VAR_2": "TMP_2maboveground",
                  "INPUT_VAR_1": "precip_rate"
                },
                "uses_forcing_file": false
              }
            }
          ]
        }
      }
    ],
    "forcing": {
      "file_pattern": ".*{{id}}.*.csv",
      "path": "./data/forcing/"
    }
  },
  "time": {
    "start_time": "2015-12-01 00:00:00",
    "end_time": "2015-12-30 23:00:00",
    "output_interval": 3600
  }
}