Preserve dtype on reset_index() in an empty DataFrame
-  closes #19602

Hello @vaibhawc! Thanks for submitting the PR.

 - There are no PEP8 issues in the file [`pandas/core/frame.py`](https://github.com/vaibhawc/pandas/blob/98629b2f342713b205fedd651299f5338b424f07/pandas/core/frame.py) !

 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23856?src=pr&el=h1) Report
> Merging [#23856](https://codecov.io/gh/pandas-dev/pandas/pull/23856?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/20ae4543c1d8838f52229830bfae0cc8626801bb?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/23856/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23856?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #23856   +/-   ##
=======================================
  Coverage   92.28%   92.28%           
=======================================
  Files         161      161           
  Lines       51500    51500           
=======================================
  Hits        47528    47528           
  Misses       3972     3972
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.68% <100%> (ø)` | :arrow_up: |
| #single | `42.31% <0%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/23856?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/23856/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.02% <100%> (ø)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23856?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23856?src=pr&el=footer). Last update [20ae454...98629b2](https://codecov.io/gh/pandas-dev/pandas/pull/23856?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Thanks for the contribution @vaibhawc can you add unit tests and a whatsnew note on what is being fixed? Closing as stale, @vaibhawc if you want to continue working on it, please address comments and reopen the PR.