GithubImporter: Ensure to fail and log imports on exceptions

What does this MR do?

Currently, the Github Importer might end up stuck even after failing to import the git repository. This might also happen when importing other types of objects from Github.

To provide better feedback to the end user this kind of exception will now mark the import (import_state) as failed. Also, to provide information to developers and testers the exceptions errors will be logged (importer.log) and saved in the import_failures table.

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What was done

• Created Gitlab::Import::ImportFailureService: This way we now have a standard way to log exceptions/errors that happens while importing a project;
  • All the exceptions/errors are logged to the importer.log with a standard format;
  • All the exceptions/errors are tracked in Gitlab::ErrorTracking;
  • All the exceptions/errors are recorded in the import_failures table;
  • When required, the exception/error might mark the whole import as failed;
  • This was created in a more generic way because it can later be used in the other importers (bitbucket, gitlab, etc);
• Updated Github Importer workers/importers to leverage of the Gitlab::Import::ImportFailureService;
• Updated Gitlab::GithubImport::Queue, to use Gitlab::Import::ImportFailureService when jobs exhausted retries;
• Updated Gitlab::Import::StuckImportJob to use Gitlab::Import::ImportFailureService;
  • This is also used in the Jira importer;

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Related to: #335660 (closed)

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How to setup and validate locally (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.

Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team