FIX Don't rely on inaccessible packages when fetching update info.

[GuySartorelli]

Fixes #49

Composer wants to use information about all dependencies when reporting the most up-to-date version that meets the project's stability/version constraints and doesn't conflict with any other dependencies.
If a dependency is inaccessible (e.g. private repositories or IP-restricted hosting) composer will fail to declare a version candidate, which results in missing information even for some accessible packages.

By ommitting inaccessible repositories, we do at least get some version information, even if there is a change of compatibility issues.

All #49 is asking for is a way to suppress the below logging for specific packages. It looks like the only thing that we really need to do is check before logging if this is one of the repositories to suppress for - but the packages being checked for updates are not necessarily the packages that can't be fetched.

silverstripe-composer-update-checker/src/Extensions/CheckComposerUpdatesExtension.php

Lines 62 to 67 in ba8bae9

	} catch (RuntimeException $ex) {
	// If exceptions are thrown during execution, fail gracefully and allow the rest of the report
	// generation to continue
	$updates = [];
	Injector::inst()->get(LoggerInterface::class)->debug($ex->getMessage());
	}

Ultimately what is happening is this:

• Composer gets a list of packages from the project's composer.json file.
• Update checker, to find the latest version that can be used, asks for the "best candidate" version for each package.
• Composer checks against all dependencies which checking for the "best candidate" for any conflicts.
• To check all dependencies composer attempts to fetch repository information for each dependency
• When composer fails to fetch repository information for a dependency, it throws an exception.

This means that the package it's trying to get update information for (which is not necessarily the same package that it can't fetch information for) doesn't get the update information stored against it in the report. This PR allows composer to use all the information it can access to give a version candidate. There is a chance of conflicts, but this is better than having no update information at all, IMO.

[GuySartorelli]

Oops, I forgot to update something.... I can't mark this as draft so consider this comment the "I am marking this as draft" button.
Edit: Found the "Convert to draft" link, but I've already made the changes now 😅

[GuySartorelli]

Okay, ready for review.