Merge Basic/Digest auth into one preemptive provider (#199)

* Remove DomainBasicAuthProvider and DomainDigestAuthProvider, introduce PreemptiveBasicDigestAuthProvider

* Improve preemptive auth provider to derive scheme from actual request for retries

Update README with "Who uses" section

Adhere to best practices of library maintaince (#195)

* Update CHANGELOG.md, README.md, and add proper versioning to releases

* Migrate from groovy to kotlin

GetETag: don't ignore weakness indicator (#8)

* GetETag: don't use .let too much, add tests

* Added `weak` attribute

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Added tests for `weak` attribute

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Added tests for `weak` attribute

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Documented `eTag` and `weak`

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Refactor `weak` setting

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Using JUnit's `assertTrue`

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Use assertTrue / assertFalse

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>
Co-authored-by: Ricki Hirner <hirner@bitfire.at>

Update README

Improve XML signature detection (minor change); remove CHANGELOG

Fix Maven package building

Version bump to 2.1.2

Version bump to 2.1.1

Update Changelog