Improved Logging for UKHPI

This PR is to handle the logging in a manner following the logging guidelines and will resolve ticket #104

Added NoMethodError rescue clause set to debug level to reduce loggin noise in production as this should be caught in development and test environments.
Improved logging status with allowance for the differences between 400 and 500 errors handled by the same method.
- resolves GH-105
Resolves error level reported to match logs where the logging was reporting 400 instead of 500
- resolves GH-105
Improved logging in perform_query method by combining generated logs into single log for better message
Updated errors reported as info level to error level
- also resolves the DEBUG level logs seen in production issue.
Improved logging in perform_query method by combining generated logs into single log for better message

Additional Changes

Now uses the proper logging level as well as provides more details to the logs for the json_rails_logger gem
Updated header links to apply the appropriate language to the root link
Refactored cache control
- resolves GH-114
Resolves rubocop OpenStruct warning
Improved webpacker setup to match newer applications
Improved Javascript asset delivery by adding defer to the script tags. If the defer attribute is set, it specifies that the script is downloaded in parallel to parsing the page, and executed after the page has finished parsing.
Improved logging by using blocks instead of strings as Ruby has to evaluate these strings, which includes instantiating the somewhat heavy String object and interpolating the variables, and which takes time. Therefore, it's recommended to pass blocks to the logger methods, as these are only evaluated if the output level is the same or included in the allowed level (i.e. lazy loading). Documentation
Removed sentry logging from dev instance
Updated the data_service_api gem to the latest 1.4.0 minor release version.
- Also includes minor patch updates for other gems, please see the Gemfile.lock for details.