Auto merge of #18680 - MortimerGoro:android_flavors, r=larsbergstrom

Implement Gradle flavors for Android VR compilations

<!-- Please describe your changes on the following line: -->

This PR adds support to easily generate Android VR builds. Rust/Java VR dependencies are not added by default.

Default build (No VR support)
```
./mach build --release --android
./mach package --release --android
./mach install --release --android
```

GoogleVR builds (e.g. Daydream)
```
./mach build --release --android --features googlevr
./mach package --release --android --flavor googlevr
./mach install --release --android
```

OculusVR builds (e.g. Gear VR)
```
./mach build --release --android --features oculusvr
./mach package --release --android --flavor oculusvr
./mach install --release --android
```

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

<!-- Either: -->
- [x] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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components/servo/Cargo.toml

@@ -17,6 +17,8 @@ max_log_level = ["log/release_max_level_info"]
 webdriver = ["webdriver_server"]
 energy-profiling = ["profile_traits/energy-profiling"]
 debugmozjs = ["script/debugmozjs"]
+googlevr = ["webvr/googlevr"]
+oculusvr = ["webvr/oculusvr"]
 
 [dependencies]
 bluetooth_traits = {path = "../bluetooth_traits"}

components/webvr/Cargo.toml

@@ -9,13 +9,17 @@ publish = false
 name = "webvr"
 path = "lib.rs"
 
+[features]
+googlevr = ['rust-webvr/googlevr']
+oculusvr = ['rust-webvr/oculusvr']
+
 [dependencies]
 canvas_traits = {path = "../canvas_traits"}
 euclid = "0.15"
 ipc-channel = "0.8"
 log = "0.3"
 msg = {path = "../msg"}
-rust-webvr = {version = "0.8", features = ["openvr"]}
+rust-webvr = {version = "0.9", features = ["openvr"]}
 script_traits = {path = "../script_traits"}
 servo_config = {path = "../config"}
 webvr_traits = {path = "../webvr_traits" }

components/webvr_traits/Cargo.toml

@@ -12,5 +12,5 @@ path = "lib.rs"
 [dependencies]
 ipc-channel = "0.8"
 msg = {path = "../msg"}
-rust-webvr-api = {version = "0.8", features = ["serde-serialization"]}
+rust-webvr-api = {version = "0.9", features = ["serde-serialization"]}
 serde = "1.0"