fix: do not freeze when downloading the logs

[imobachgs]

Problem

If you try to download the logs using the web UI, agama-web-server gets unresponsive.

Solution

• Use tokio::process::Command to download the logs.
• Rename the endpoint to reflect the file format.

To do

• The UI is not properly adapted yet but @dgdavid is working on it.

[dgdavid]

LGTM, thank you!

[coveralls]

Pull Request Test Coverage Report for Build 11483204391

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 2 (0.0%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.003%) to 71.39%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
rust/agama-server/src/manager/web.rs	0	2	0.0%

Files with Coverage Reduction	New Missed Lines	%
rust/agama-server/src/manager/web.rs	1	0.0%

Totals
Change from base Build 11460749266:	-0.003%
Covered Lines:	16883
Relevant Lines:	23649

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💛 - Coveralls