Add automatic JS license generation

[silverwind]

Removed librejs file and replaced it with a plaintext file that is built from all JS dependencies that are included in the webpack build. It does not cover the few remaining statically vendored files and fomantic is added manually because it's not yet in the webpack build process.

Fixes: #11630

Sample License (source):

--------------------------------------------------------------------------------
fomantic-ui@2.8.5 - MIT
--------------------------------------------------------------------------------
# The MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the 'Software'), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

[6543]

lint error

[silverwind]

Lint fixed. Fingers crossed the integration test passes.

[silverwind]

Completed GET /js/licenses.txt 404 Not Found in 331.473µs
    links_test.go:41: 
          Error Trace:  integration_test.go:427
                              links_test.go:41
          Error:        Not equal: 
                        expected: 200
                        actual  : 404
          Test:         TestLinksNoLogin
          Messages:     Request: GET /js/licenses.txt

I guess webpack files are not available by the time these test run. Should I just remove that test or try getting the webpack build in? (which might cause the tests to run 2-3 mins longer)

[6543]

@silverwind I think we can remove this url from the test

[silverwind]

You're right. While I do think that there is some value in testing the webpack build output, it's probably not warranted the extra load it creates on CI. Frontend build was removed in #11159 from the testing steps, btw.

[lafriks]

But it is not compatible with librejs imho

[silverwind]

LibreJS is a meme imho. Its Firefox extension has a whopping 257 users and their approach can not possibly work with bundlers like webpack anyways.

[silverwind]

I'm not against the idea of librejs but I see no sane way of handing out the licensing info in a parsable format. Of course, if there is a webpack plugin to handle this task, I'm all for adding it, but there appears to be none. We certainly don't want to manually handle this like we did before (the file had many errors and was generally inaccurate because it did not list indirect dependencies).

Also see https://lists.gnu.org/archive/html/bug-librejs/2019-02/msg00003.html

[6543]

🚀

[silverwind]

BTW we do have the option to generate HTML as well using this mechanism but I see no point in doing it just for Librejs because they can only block non-free scripts on a per-file level so for example would block our index.js chunk if one of the modules within is non-free so the approach with the HTML is systematically flawed and the only proper way to do it would be inline comments in the js files but Librejs does not yet support that.

[silverwind]

Rebased and added one more tweak that localizes the previously hardcoded word licenses.

[silverwind]

Reduced footer text to just "Licences". I feel it's not fully correct to label them as JS as we're also depending on modules that only provide like svg/css/fonts and more.

[silverwind]

With vendored golang dependencies, it shouldn't be too hard to also add them to the output. Once they are unvendored, it will be more tricky thought and we'd probably need a tool to retrieve them.