Remove unnecessary `as_tibble` calls

[frank113]

This pull request addresses issue #222 by removing unnecessary as_tibble calls.

Changes made:

• Added unit test of check_is_data_like in newly-created test-util.R to validate behavior
• Removed as_tibble call in model_frame as it repeats logic performed in check_is_data_like that coerces the first parameter to a tibble.
  • I left the as_tibble call in check_is_data_like to ensure that the data field of model_frame will always be a tibble.
• Added unit test of model_frame to ensure that the data field will always be a tibble

as_tibble occurs 7 times in the code as of the time of this comment at commit c2c896cf1141883533ce5d4ad37e80fd6284c92a. To remove redundant calls we will examine the following uses:

1. model_frame in R/model-frame.R:
   • The data parameter is passed through the check_is_data_lake. For check_is_data_like to succeed the data parameter must be either a data.frame or matrix
   • I added tests in test-util.R that confirms the behavior of

[frank113]

Did not mean to open, will re-open when work is completed.

[github-actions[bot]]

This pull request has been automatically locked. If you believe you have found a related problem, please file a new issue (with a reprex: https://reprex.tidyverse.org) and link to this issue.