Added:
- Filter "timber/image_helper/pre_analyze_url" to short-circuit the method's default URL analysis logic.
- Filter "timber/image_helper/analyze_url" to mutate the analyzed URL components.

Added:
- Filter "timber/image_helper/pre_theme_url_to_dir" to short-circuit the method's default path resolution logic.
- Filter "timber/image_helper/theme_url_to_dir" to mutate the resolved path.

Renamed from `$components` to `$info`.

Moved original URL parsing from `analyze_url()` to new method `_analyze_url()`.

Changed logic of filters; "timber/image_helper/pre_analyze_url" controls whether the original logic is called, to ensure the "timber/image_helper/analyze_url" filter is always applied.

Moved original URL conversion from `theme_url_to_dir()` to new method `_theme_url_to_dir()`.

Changed logic of filters; "timber/image_helper/pre_theme_url_to_dir" controls whether the original logic is called, to ensure the "timber/image_helper/theme_url_to_dir" filter is always applied.

If any symbolic links in `TMPDIR` are not resolved, usage of `realpath()` risks paths being broken such as by `ImageHelper::analyze_url()` calling `URLHelper::remove_url_component()` to remove `WP_CONTENT_DIR`.

Given a WordPress installation at:

```sh
/var/folders/XX/XXXXXXXXXX/X/wordpress/
```

And the following URL:

```sh
http://example.org/wp-content/themes/timber-test-theme/assets/images/cardinals.jpg
```

The `ImageHelper::theme_url_to_dir()` method would return the following absolute path (which internally calls `realpath()`):

```sh
/private/var/folders/XX/XXXXXXXXXX/X/wordpress/wp-content/themes/timber-test-theme/assets/images/cardinals.jpg
```

The `ImageHelper::analyze_url()` method would return the following components:

```php
[
  'url'       => 'http://example.org/wp-content/themes/timber-test-theme/assets/images/cardinals.jpg',
  'absolute'  => true,
  'base'      => 2,
  'subdir'    => '/private/themes/timber-test-theme/assets/images',
  'filename'  => 'cardinals',
  'extension' => 'jpg',
  'basename'  => 'cardinals.jpg',
]
```

As illustrated by `subdir`, the absolute path is broken by `URLHelper::remove_url_component()` striping the symbolically linked path from the canonical path.

Changed:
- Added `set_up()` and `tear_down()` from `TestExternalImage` to prepare test environment for content directory test.
- Fixed tests of `testAnalyzeURLTheme()` based on `TestExternalImage`.

These fixes will help with adding tests for `ImageHelper::theme_url_to_dir()`.

Changed:
- Added `set_up()` and `tear_down()` to match `TestTimberImageHelperInternals` (from `TestExternalImage`) to prepare test environment for content directory test.

* 2.x: (95 commits)
  Update statements to Weak implicit
  Check expected values as suggested by @nlemoine
  fix: phpstan issues & use fully qualified imports
  Refactor file models: update phpdoc
  Refactor file models: remove file property
  Refactor file models
  Fix coding style issue
  Update method descriptions
  Update return types and documentation
  Fix is_external() to work with domains only
  Fix test
  Improve URLHelper is_local method
  Improve docblocks of URLHelper methods is_local and is_external
  Replace strstr in URLHelper is_external method
  Fix shortened return in URLHelper is_local method
  remove error_log and prefix functions
  add check to image create functions
  Run coding standard checks only with highest or stable dependencies
  Add CS fixes to ignored revs
  Fix some CS issues
  ...

Changed:
- Renamed `_analyze_url` to `get_url_components`.
- Renamed `_theme_url_to_dir` to `get_dir_from_theme_url`.