`as_fmt_char` supports standard data types

[gowerc]

Closes #119

Not even sure how this went un-detected but the lack of a default method meant things like dates / datetime were throwing errors when trying to be converted to character.

[github-actions[bot]]

Code Coverage Summary

Filename                Stmts    Miss  Cover    Missing
--------------------  -------  ------  -------  --------------------------
R/ascii_tables.R          114       8  92.98%   10, 154, 164, 169-172, 231
R/cast_variables.R         49       0  100.00%
R/diffdf.R                188      18  90.43%   358-375, 402
R/generate_keyname.R       10       1  90.00%   16
R/identify.R              152       8  94.74%   283-290
R/is_different.R           52       0  100.00%
R/issuerows.R              40       0  100.00%
R/issues.R                 17       1  94.12%   51
R/misc_functions.R         34       2  94.12%   9, 13
R/print.R                  20       0  100.00%
TOTAL                     676      38  94.38%

Results for commit: 20716b337b7c336b762ec268cbca2f655c5be148

Minimum allowed coverage is 80%

:recycle: This comment has been updated with latest results

[github-actions[bot]]

Unit Tests Summary

  1 files   12 suites   6s :stopwatch:  51 tests  49 :white_check_mark: 2 :zzz: 0 :x: 582 runs  574 :white_check_mark: 8 :zzz: 0 :x:

Results for commit 20716b33.

:recycle: This comment has been updated with latest results.