Add the option to only show the configuration for a single project

[bouweandela]

Description

Example usage:

$ esmvaltool config show --project CMIP7

prints

# Current configuration for project 'CMIP7', excluding the keys 'extra_facets':
projects:
  CMIP7:
    cmor_table:
      paths:
      - cmip7/tables
      - cmip6-custom
      type: esmvalcore.cmor.table.CMIP6Info
    data:
      local:
        dirname_template: '{drs_specs}/{project}/{activity}/{institute}/{dataset}/{exp}/{ensemble}/{region}/{frequency}/{short_name}/{branding_suffix}/{grid}/{version}'
        filename_template: '{short_name}_{branding_suffix}_{frequency}_{region}_{grid}_{dataset}_{exp}_{ensemble}*.nc'
        rootpath: ~/climate_data
        type: esmvalcore.io.local.LocalDataSource
    preprocessor_filename_template: '{short_name}_{branding_suffix}_{frequency}_{region}_{grid}_{dataset}_{exp}_{ensemble}'

Link to documentation:

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.70%. Comparing base (69f2019) to head (46c6252).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3020   +/-   ##
=======================================
  Coverage   95.70%   95.70%           
=======================================
  Files         267      267           
  Lines       15768    15774    +6     
=======================================
+ Hits        15090    15096    +6     
  Misses        678      678           

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