fix typo(s)

Return null instead of empty array

Keep logging functionality out of the public API as requested in https://github.com/dlang/dub/pull/2124#issuecomment-813016939.

Fix indentation style, now using tabs

New logging module - initial functionality ...

The new module replaces dub.internal.vibecompat.core.log by using the
same function names, but implementing colored output and the left
fixed-width tag. Overloaded functions are provided to output colored
text.

Still missing initLogging() and non-TTY stdout/stderr detection

Trivial: Fix syntax for Params documentation in packagesuppliers

Use Dependency.any whenever possible

Trivial: Remove trailing whitespace

Avoid needless string concat in log calls

fix: parse version from filesystem supplier correctly

RegistryPackageSupplier.genPackageDownloadUrl added

Remove usage of deprecated std.xml

Use queryString to setup the pacakge parameters

Replace calls to NativePath.toString() with .name ...

This has been deprecated in vibe-core and only triggers with 'library-nonet'.

Enable exact search for maven registry provider

Increased maven http timeout

Don't catch failed metadata requests with a Json(null) object

Update registry URL + test payload

Update package dependency URL

use single api request to fill metadata cache for all dependencies ...

- avoids various RTTs and possible failures

Use new minimized API endpoint for package queries

Merge remote-tracking branch 'upstream/stable' into merge_stable

avoid using failing fallback package suppliers for 10 minutes ...

- still keep retrying primary package supplier

improve package supplier fallback logic ...

- scope (failure) did swallow fatal errors
- improve logging of failures and successes
- rethrow failure of default registry instead of from the last one
- remove failing package suppliers, so we don't keep beating dead horses

Note that some retry logic is already done interally by package suppliers,
so a failing one is unlikely to recover on the next usage.

Filesystem package supplier updated

Retry download for registry search packages

Refactor retry download

Split-up package suppliers into individual modules