fix(windows): fix URL handling when opening browser

[rami3l]

Closes #5035 by:

• Reverting the partial hack in Only create a URL when opening docs with URI fragments #5036;
• Upgrading opener to a newer version that includes Fix Windows file URL handling and browser fragment preservation Seeker14491/opener#44.

Many thanks to @ChrisDenton for investigating into this issue and @Seeker14491 for making the upstream fix!

cc @SnipUndercover if you want to do another round of testing with the two commands below:

> rustup doc --rustdoc
> rustup doc --rustdoc lints::broken_intra_doc_links

[SnipUndercover]

Checked out af4c8c2 and can confirm that the issue is resolved.

Running rustup with $env:BROWSER set and unset both result in successfully opening a new browser tab with the correct link.
Tried with the following commands:

cargo run-rustup -- doc --book
cargo run-rustup -- doc --rustdoc
cargo run-rustup -- doc --rustdoc lints::broken_intra_doc_links

cd target\debug
$env:RUSTUP_FORCE_ARG0="rustup"
./rustup-init doc --book
./rustup-init doc --rustdoc
./rustup-init doc --rustdoc lints::broken_intra_doc_links

Happy to see this fixed!

[ChrisDenton]

I have been testing across a few different environments and it seems to work fine for me. So looks good to me!

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