Cran network stable fixes (#228)

[pbulsink]

Per the request from CRAN and closes #228: this should now fail gracefully (return NULL) for any Ergast function if there's a connection/internet issue, and the code has been abstracted to be more general. It will also display a message with the failure to get Ergast data.

Previous behaviour was to fail with a warning (against CRAN policy) and harder-coded data manipulation wasn't flexible against small changes in results returned. This should be more forgiving now.

Notable adds:

• add_col_if_absent(data, column, na_type) - a new function that adds a column of specified NA_type_ (or generic NA) to a data.frame (or higher abstract) if it's absent. Returns the data.frame as a tibble. Has no effect if the column is already present.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 89.79592% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 93.95%. Comparing base (0041c82) to head (5496bbc).

:exclamation: Current head 5496bbc differs from pull request most recent head 1a20e27. Consider uploading reports for the commit 1a20e27 to get more accurate results

Files	Patch %	Lines
R/load_laps.R	50.00%	2 Missing :warning:
R/load_constructors.R	50.00%	1 Missing :warning:
R/load_drivers.R	93.75%	1 Missing :warning:
R/load_pitstops.R	50.00%	1 Missing :warning:
R/load_quali.R	94.11%	1 Missing :warning:
R/load_results.R	83.33%	1 Missing :warning:
R/load_schedule.R	97.36%	1 Missing :warning:
R/load_sprint.R	50.00%	1 Missing :warning:
R/load_standings.R	50.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #229 +/- ## ========================================== - Coverage 95.16% 93.95% -1.21% ========================================== Files 19 19 Lines 600 596 -4 ========================================== - Hits 571 560 -11 - Misses 29 36 +7 ```

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[pbulsink]

@SCasanova still need to validate code works with no internet connection. Seems like there's not a really easy way of specifying it in test without adding code switches (see https://community.rstudio.com/t/unit-testing-for-non-working-internet-connection/31894 or https://blog.r-hub.io/2023/01/23/code-switch-escape-hatch-test/ ).