Adding bootstrap configs for collection and new historical variables

[ricardogsilva]

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NOTE

For consistency, this PR includes a change in the name of the configuration parameters used by the forecast datasets to indicate their respective year period. Changes are:

• DJF -> winter
• MAM -> spring
• JJA -> august
• SON -> autumn
• year -> all_year

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This PR adds the relevant bootstrap configurations for the new historical datasets:

• tdd
• tnd
• txd
• tr
• fd
• cdds
• hdds
• su30
• prcptot

These are included in their respective 30-year, and annual series. The 10-year series are not included here, as they are still being modified by the client.

In order to support these datasets, the following new configuration parameters are also added:

• archive, which can be either historical or forecast and helps distinguish the two types of coverages that are now supported by the system
• historical_variable, which contains entries for the new variables
• historical_year_period, which features the year periods recognized by the new datasets (A00, S01, S02, ...)
• climatological_standard_normal, which contains the relvant climate normal year intervals (1991-2020, etc.)

Additionally, in order to support the new ways by which the underlying NetCDF datasets are structured, this PR adds some new features:

• a configuration parameter now has the internal_value property, which is used when building THREDDS and WMS identifiers. This allows decoupling a parameter's name, which is what is used in the identifiers that are visible to the outside of the system, from their corresponding values, which are used in internal components. This was notoriously needed also for referring to the pattern used in historical NetCDF datasets for identifying the climate normal, which is a string of the form "yyyy-yyyy" - the problem here was that the system was relying on conf parameter names not being allowed to have the - character. With the introduction of a param's internal_value this is no longer a problem
• a coverage configuration's wms_main_layer_name can now be a templated string, allowing for the underlying NetCDf variable names to vary according with the configuration parameters - example: {observation_year_period}_avg
• a coverage configuration's thredds_url_pattern can now be defined with an fnmatch pattern, thus allowing NetCDF names to vary - in this case the system will perform an additional request to the THREDDS server in order to scan the catalog in order to find the actual name of the file, caching the results

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• fixes Add configuration for the new historical netCDF datasets #209
• fixes Need to be able to access multiple netcdf variables in the same file #228