Standardize function signatures
Standardize the following function signatures:

1) `repeat(reps, *args, **kwargs)`
2) `searchsorted(value, side='left', sorter=None)`

Closes #12662.
## [Current coverage](https://codecov.io/gh/pandas-dev/pandas/pull/14645?src=pr) is 85.22% (diff: 97.67%)
> Merging [#14645](https://codecov.io/gh/pandas-dev/pandas/pull/14645?src=pr) into [master](https://codecov.io/gh/pandas-dev/pandas/branch/master?src=pr) will increase coverage by **<.01%**

```diff
@@             master     #14645   diff @@
==========================================
  Files           143        143          
  Lines         50807      50813     +6   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits          43297      43304     +7   
+ Misses         7510       7509     -1   
  Partials          0          0          
```

> Powered by [Codecov](https://codecov.io?src=pr). Last update [d8e427b...f448639](https://codecov.io/gh/pandas-dev/pandas/compare/d8e427bda07fc350dfa327df43b790697e733747...f4486393ea0c0953769aa0237b6186324e85aa07?src=pr) @jreback , @chris-b1  : Everything looks green.  Ready to merge if there are no concerns.
 lgtm.
 @jreback , @jorisvandenbossche : Everything seems to be passing still.  Ready to merge if there are no other concerns. @jreback , @jorisvandenbossche : Changes made, and everything seems to be passing still.  Ready to merge if there are no other concerns. @gfyoung Thanks!