Integrate Configy colored output with dub's

dub search: Improve text, rename parameter ...

The 'query' name is inaccurate, as we only ever expect a package name.

Dub.fetch: Remove a redundant getPackage call ...

Since storeFetchedPackage already returns the Package.

Trivial: Deprecate a compatibility overload of Dub.remove

dub.fetch: Do not catch Exception when a local package can't be loaded ...

Given how simple the function being called is,
there is no reason for us to ignore this error.

Trivial: Remove workaround for DMD v2.070

Trivial: Fix indentation of a log statement

Deprecate duplicated enum LocalPackageType -> PlacementLocation ...

Two enums, both have the same values, in the same order.

settings/selections: Only warn on unknown keys, add changelog ...

This will give users the time to adapt, without erroring right away.

Support escaped forward slashes in YAML parser ...

Integrate fix for issue dlang-community/D-YAML#302 .

Move environment read outside of DependencyResolver ...

Reading environment variables from random places in the code makes
the flow harder to follow, and unittesting harder.
This moves one environment reads to the `dub` module,
which performs many of them already.

Parse settings.json using configy ...

This will provide superior error messages to the user,
and match what we already do for `dub.selections.json`.

It also allows us to remove many fields from the `Dub` class.
Those fields existed so that we would not have to re-compute the data
from the JSON DubConfig was storing. Now that we use a simple struct,
and do the aggregation eagerly, all of that complexity can go.

Incorporate review by Jan Jurzitza <gh@webfreak.org>.

Address review by WebFreak001.

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

Output improvements in package management ...

(dub fetch and dub remove)

Improved dub init output ...

Remove duplicate message (package created in ...) and using colored tag

More improvements and replacements ...

Adapted generators output to new style, small change for non-selected
packages

Making the output prettier - first changes

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

Unify package path in a single PackageManager function ...

The idea is that PackageManager should be responsible for packages on the disk,
and the first step to do that is remove the leakage of path happening in the Dub class.

Trivial: Deprecate Dub.remove(Package, bool) ...

The corresponding PackageManager function is long deprecated,
but the Dub wrapper was not deprecated.

SpecialDirs: Re-order by priority, document

Refactor SpecialDirs initialization in its own function ...

Take the IO-performing code in a single function so later on
we can better isolate it for library users.

Trivial: Deduplicate GeneratorSettings initialization

Trivial: Remove a leftover debug statement

Deprecate `PackageManager.loadSCMPackage` & other `Dependency`-related refactoring (#2312) ...

* Trivial: Take a nested function out of a foreach loop

* Deprecate PackageManager.loadSCMPackage's Dependency overload, use Repository

We're moving away from using `Dependency.m_range` to store the git ref,
and the `Repository` type has already been updated to include the information,
but some places still read it from `m_range`, including this one.

* Trivial: Forward Dependency's string ctor to VersionRange ctor

* Trivial: Simplify comparison with `VersionRange.Invalid` within `VersionRange`

SelectedVersions: Add Repository to overload set (#2314) ...

Before it was an independent function because it had a different set of parameters,
but now that it has been unified, we can put it in the overload set.
No deprecation since the previous change that deprecated selectVersionWithRepository
hasn't been released yet.

Various code simplification around `dub.selections.json` (#2311) ...

* Deprecate unused Json constructor

* Trivial: Fix import order in dub.project

* Simplify DependencyResolver filtering

DependencyResolver is only instantiated from one place, and never re-used.
It makes more sense to set those variables in the constructor,
and avoid repeatedly calling a single function.

* Move file format to dub.selections.json to its own struct

Our goal is to replace the handcrafted JSON code with configy.

Trivial: Remove an always-true if (#2313) ...

Since we are using a path-based dependency, dep.matches will always return true.