[BUG] [copilot] File extensions are missing when copilot downloads Blob/FlyteFile inputs

### Flyte & Flytekit version

Flyte 1.16

### Describe the bug

Copilot today has the following behavior:

```
# ContainerTask, as an example
def t1(file: FlyteFile["csv"]):
... # copilot downloads the file to e.g. /inputs/file
```

Sometimes, this is unintuitive (perhaps a bug? or an enhancement request? not clear...) and it may be expected that the file is downloaded to `/inputs/file.csv` instead.

### Expected behavior

The file is downloaded to `/inputs/file.csv` instead. However, the "bugfix" must be done carefully, as it is likely that existing workflows are already expecting the file to be downloaded to `/inputs/file`.

### Additional context to reproduce

_No response_

### Screenshots

_No response_

### Are you sure this issue hasn't been raised already?

- [x] Yes

### Have you read the Code of Conduct?

- [x] Yes