Document config parameters in plugins

[alambare]

Is your feature request related to a problem? Please describe.
Add docstring documentation for config parameters available in each plugin.

Describe the solution you'd like
Use docstring to document the parameters available for each plugin.
Should be described for each parameter:

• the parameter name
• a description explaining what is it for, what does it do
• format and type of expected value
• whether it is optional or mandatory
• default value

plugins to cover:

Api

• EcmwfApi
• UsgsApi

Authentication

• AwsAuth
• GenericAuth
• HTTPHeaderAuth
• KeycloakOIDCPasswordAuth
• OAuth
• OIDCRefreshTokenBase
• OIDCAuthorizationCodeFlowAuth
• HttpQueryStringAuth
• QueryStringAuth
• RequestsSASAuth
• SASAuth
• TokenAuth
• OIDCTokenExchangeAuth

Crunch

• FilterDate
• FilterLatestIntersect
• FilterLatestByName
• FilterOverlap
• FilterProperty

Download

• AwsDownload
• CreodiasS3Download
• HTTPDownload
• S3RestDownload

Search

• BuildPostSearchResult
• BuildSearchResult
• CopMarineSearch
• CreodiasS3Search
• CSWSearch
• DataRequestSearch
• QueryStringSearch
• ODataV4Search
• PostJsonSearch
• StacSearch
• StaticStacSearch

[jlahovnik]

Is your feature request related to a problem? Please describe. Add docstring documentation for config parameters available in each plugin.

Describe the solution you'd like Use docstring to document the parameters available for each plugin. Should be described for each parameter:

* the parameter name

* a description explaining what is it for, what does it do

* format and type of expected value

* whether it is optional or mandatory

* default value

plugins to cover:

Api

* [x]  EcmwfApi

* [x]  UsgsApi

Authentication

* [x]  AwsAuth

* [x]  GenericAuth

* [x]  HTTPHeaderAuth

* [x]  KeycloakOIDCPasswordAuth

* [x]  OAuth

* [x]  OIDCRefreshTokenBase

* [x]  OIDCAuthorizationCodeFlowAuth

* [x]  HttpQueryStringAuth

* [x]  QueryStringAuth

* [x]  RequestsSASAuth

* [x]  SASAuth

* [x]  TokenAuth

* [x]  OIDCTokenExchangeAuth

Crunch

* [x]  FilterDate

* [x]  FilterLatestIntersect

* [x]  FilterLatestByName

* [x]  FilterOverlap

* [x]  FilterProperty

Download

* [x]  AwsDownload

* [x]  CreodiasS3Download

* [x]  HTTPDownload

* [x]  S3RestDownload

Search

* [x]  BuildPostSearchResult

* [x]  BuildSearchResult

* [x]  CopMarineSearch

* [x]  CreodiasS3Search

* [x]  CSWSearch

* [x]  DataRequestSearch

* [x]  QueryStringSearch

* [x]  ODataV4Search

* [x]  PostJsonSearch

* [x]  StacSearch

* [x]  StaticStacSearch

NOTE: RequestsSASAuth and QueryStringAuth aren't plugins and therefore don't have a config