Added IPNS keys manager UI to IPFS Settings

[spylogsster]

Resolves brave/brave-browser#15566

• Added "Import" button to dialog that allows to import a key with predefined name
• Renamed button from Submit to Generate to be consistent with another button
• Implemented some refactoring because I reuse file uploads logic to ipfs node (Moved all network blobs constructions to ipfs_network_utils, there are some related changes in import classes. Finally refactoring will be finished in next PR in Remove redundant classes for import brave-browser#15758)
• Added alertion about error if import was not successful

Submitter Checklist:

• I confirm that no security/privacy review is needed, or that I have requested one
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally: npm run test -- brave_browser_tests, npm run test -- brave_unit_tests, npm run lint, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

• Check if IPFS import works as expected and files/directories/links are imported well
• Export keys from node on any computer via ipfs key export -o ./mykey.key mykey command and import it via brave://settings/ipfs/keys
• Check if you import not a key file(wrong format or broken) there is alertion about error

[mkarolin]

s/import/generate in the desc

[mkarolin]

chromium_src ++

[iefremov]

@bbondy @spylogsster I was just randomly browsing for Unretained pointers - this is an easily reproducible crash. Just start an import of a file and quickly close the settings tab (to 100% reproduce pick up any large file, I've tried with videos).

Basically the first thing I do during reviews is Ctrl-F Unretained - hope this could help to prevent future crashes

Received signal 11 SEGV_MAPERR ffffd859ca3ff9df
#0 0x7f4936df7659 base::debug::CollectStackTrace()
#1 0x7f4936cf63f3 base::debug::StackTrace::StackTrace()
#2 0x7f4936df71b0 base::debug::(anonymous namespace)::StackDumpSignalHandler()
#3 0x7f49260363c0 (/usr/lib/x86_64-linux-gnu/libpthread-2.31.so+0x153bf)
#4 0x7f4934c79237 content::WebUIMessageHandler::IsJavascriptAllowed()
#5 0x562157e1730f content::WebUIMessageHandler::FireWebUIListener<>()
#6 0x562157e171ed BraveDefaultExtensionsHandler::OnKeyImported()
#7 0x5621577ab147 ipfs::IpnsKeysManager::OnKeyImported()
#8 0x5621577abef9 base::internal::FunctorTraits<>::Invoke<>()
#9 0x5621577abe27 base::internal::Invoker<>::RunOnce()
#10 0x7f49307157ed _ZNO4base12OnceCallbackIFvNSt4__Cr10unique_ptrINS1_12basic_stringIcNS1_11char_traitsIcEENS1_9allocatorIcEEEENS1_14default_deleteIS8_EEEEEE3RunESB_
#11 0x7f4930715f4e network::(anonymous namespace)::SimpleURLLoaderImpl::FinishWithResult()
#12 0x7f4930713fea network::(anonymous namespace)::SimpleURLLoaderImpl::OnReceiveResponse()
#13 0x7f493075050a network::mojom::URLLoaderClientStubDispatch::Accept()
#14 0x7f4936694dab mojo::InterfaceEndpointClient::HandleValidatedMessage()

[spylogsster]

thanks brave/brave-browser#15961

[iefremov]

Here weak_factory_ is redundant, because the manager owns url loaders, and it will destroy loaders in its destructor. Loaders cancel their callbacks when destroyed