Support minimum JDK of 11+ and minimum of Android API 33+

Per [Jakarta EE Platform 10](https://jakarta.ee/specifications/platform/10/):
>Minimum Java SE Version
>Java SE 11 or higher

This means that Angus Mail would no longer be building for JDK 8. Moving an Android API version 26+ or greater will give access to `java.lang.invoke`, `java.util.Base64`, and `java.time`. However, all versions prior to Android 13 (API level 33) will be deprecated so we must assume API level 33 Android is required. API 26+ may be able to run with Angus Mail but, is not supported and we will close any tickets that are not meeting the API requirements.

Per [Meet Google Play's target API level requirement](https://developer.android.com/google/play/requirements/target-sdk):

> Starting on August 31, 2023:
>
> New apps must target Android 13 (API level 33) or higher; except for [Wear OS](https://developer.android.com/wear) apps, which must target a version between Android 11 (API level 30) and Android 13 (API level 33), inclusive.
>
> App updates must target Android 13 or higher and adjust for behavioral changes in Android 13; except for Wear OS apps, which must target Android 11.
>
>Permanently private apps—which are restricted to users in a specific organization and are intended for internal distribution only—aren't required to meet the target API level requirements.

[snip]

>...Furthermore, as of Android 10 (API level 29), users [see a warning](https://developer.android.com/about/versions/10/behavior-changes-all#low-target-sdk-warnings) when they start an app for the first time if the app targets Android 5.1 (API level 22) or lower.

Per [Which Java APIs can I use in my Java or Kotlin source code?](https://developer.android.com/build/jdks) the API level 32 and API level 33 are versions that support Java 11 source syntax. API level 34 supports Java 17 source syntax.

The [Android API Levels](https://apilevels.com/) site shows the usage of devices.

/cc @lukasj

No files or tests are named. Start by locating the project's JDK and Android API build configuration, then identify the compatibility settings and CI checks that enforce supported versions. Done means the project requires JDK 11 or newer and Android API level 33 or newer, with relevant checks passing.

Written by the indexing model from the issue text.