feat: Add User-Agent for mirroring

[terriko]

This adds a User-Agent header to cve-bin-tool, currently used only for aiohttp requests used in data_sources and mirroring. Here's what it looks like trying an experiment on localhost right now:

[terri@cedar ~]$ ls | nc -l -p 4888
GET //metadata.json HTTP/1.1
Host: 127.0.0.1:4888
User-Agent: cve-bin-tool/3.2.2dev0 (https://github.com/intel/cve-bin-tool/)
Accept: */*
Accept-Encoding: gzip, deflate

At this time, the PR doesn't cover any url loads using requests, only the ones using aiohttp

[codecov-commenter]

Codecov Report

Merging #3183 (a5cf257) into main (e2d1ef7) will decrease coverage by 2.13%.
The diff coverage is 64.28%.

@@            Coverage Diff             @@
##             main    #3183      +/-   ##
==========================================
- Coverage   81.40%   79.27%   -2.13%     
==========================================
  Files         716      714       -2     
  Lines       11114    10983     -131     
  Branches     1495     1271     -224     
==========================================
- Hits         9047     8707     -340     
- Misses       1681     1882     +201     
- Partials      386      394       +8     

Flag	Coverage Δ
longtests	?
win-longtests	79.27% <64.28%> (+0.11%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
cve_bin_tool/data_sources/rsd_source.py	0.00% <0.00%> (ø)
cve_bin_tool/data_sources/epss_source.py	69.86% <33.33%> (+0.41%)	⬆️
cve_bin_tool/nvd_api.py	19.17% <33.33%> (+0.42%)	⬆️
cve_bin_tool/data_sources/curl_source.py	98.00% <100.00%> (+0.04%)	⬆️
cve_bin_tool/data_sources/gad_source.py	74.22% <100.00%> (-10.75%)	⬇️
cve_bin_tool/data_sources/nvd_source.py	56.00% <100.00%> (+0.17%)	⬆️
cve_bin_tool/data_sources/osv_source.py	90.69% <100.00%> (+11.25%)	⬆️
cve_bin_tool/data_sources/redhat_source.py	67.76% <100.00%> (+4.84%)	⬆️
cve_bin_tool/fetch_json_db.py	49.27% <100.00%> (+0.37%)	⬆️
cve_bin_tool/version.py	94.44% <100.00%> (+0.32%)	⬆️

... and 19 files with indirect coverage changes

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[novafacing]

Looks good to me, possibly worth extending this functionality in the future!

[novafacing]

My only comment here is that this is such a good idea it may be worth adding an environment variable, command line arg, or configuration option to let the user optionally specify this value. The list of sources doesn't have anything I would anticipate adding user-agent checks, but it's possible corporate firewalls or some such thing may restrict outbound user agents.

[terriko]

Thanks all, let's get this merged!