[Elm] Fix not sanitizing param name

[Qluxzz]

From the example I added, when a schema has a property with a space in it like the following example:

schema:
  type: object
  properties:
    "name with spaces":
      type: string

The resulting function is:

paramSanitizeTestPost : Maybe String -> Api.Request ()
paramSanitizeTestPost name with spaces =
    Api.request
        "POST"
        "/param-sanitize-test"
        []
        []
        []
        (Just <| Http.multipartBody <| List.filterMap identity [ Maybe.map (Http.stringPart "name with spaces") name with spaces ])
        (Json.Decode.succeed ())

Which doesn't compile since the annotation says it should take one argument, but now it takes three (name, with, and spaces). And the same issue when we try to map it to the argument here:

(Just 
    <| Http.multipartBody 
    <| List.filterMap identity [ Maybe.map (Http.stringPart "name with spaces") name with spaces ]
                                                                                  ^----^----^
)

This PR fixes so we sanitize/normalize the param name. And also fix so we use the paramName partial when mapping multi part body arguments, which previously just used {{paramName}} to add it.

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@eriktim

[eriktim]

LGTM

[wing328]

@Qluxzz thanks for the PR

I've filed #20173 instead as we usually override toParamName to handle other edge cases such as reserved word, better support for parameter name mapping, etc.

can you please give it a try to see if this approach works for you as well?

[wing328]

@Qluxzz when you've time, can you please PM me via Slack?

https://join.slack.com/t/openapi-generator/shared_invite/zt-2uoef5v0g-XGwo8~2oJ3EoziDSO1CmdQ

[Qluxzz]

I've reworked the solution so we now override toParamName instead of using the camelcase lambda, this required some changes in the templates where we should use baseName instead of the sanitized paramName.

I also expanded the endpoint I added for testing, so it tests the different parameter types.

[wing328]

lgtm. thanks for the PR