Allow to control suffix for NamedTempFile

[MaxG87]

As described in #263 , for a test I write I need to create a temporary file that I pass on to a CLI under test. I need to choose the suffix of the file name.

I couldn't find how to do so using NamedTempFile directly. Instead, I had to use the Builder, which I found a bit cumbersome. Therefore, I wanted to ask whether it would be possible to add something like NamedTempFile::with_suffix(...) or even NamedTempFile::from_pattern.

The latter, from_pattern, would allow to use NamedTempFile a bit like Unix' mktemp, which I would find awesome.

[Stebalien]

First, I'd rather not parse templates/patterns.

In terms of with_suffix, I added support for with_prefix because it makes debugging much easier and specifying a prefix is very common. On the other hand, if you need this much control over the temporary file name, you're likely better served by using the Builder explicitly (really, it exists so that we don't have to create a bunch of one-off constructors).

Also see:

• Prefix usage: https://grep.app/search?q=Builder.%2A%5C.prefix%5C%28.%2Atemp&regexp=true&filter[lang][0]=Rust
• Suffix usage: https://grep.app/search?q=Builder.%2A%5C.prefix%5C%28.%2Atemp&regexp=true&filter[lang][0]=Rust

That's hardly perfect information, but it appears that prefix is much more common.

[MaxG87]

This sounds a very reasonable. I will stick with the Builder then. Thank you very much.