Migrate amber/web sources from javax to jakarta namespace

### Task Summary

`amber/src/main/scala/org/apache/texera/web/` has 35 files that import `javax.ws.rs`, `javax.annotation.security`, `javax.websocket`, `javax.servlet`, or `javax.validation`. Under Dropwizard 4 every one of these moves to the `jakarta.*` namespace; the JAX-RS, Servlet, WebSocket, and Bean Validation APIs are different artifacts entirely.

Scope of the replacement:

- `javax.ws.rs.*` → `jakarta.ws.rs.*` (27 files)
- `javax.annotation.security.*` → `jakarta.annotation.security.*` (~16 files, overlap with above)
- `javax.websocket.*` → `jakarta.websocket.*` (5 files; signatures change, not just imports — coordinate with the WebSocket sub-issue)
- `javax.servlet.*` → `jakarta.servlet.*` (inlined `Filter` in `ComputingUnitMaster.scala`)
- `javax.validation:validation-api:2.0.1.Final` → `jakarta.validation:jakarta.validation-api:3.x`

Companion to this is the Dropwizard package move: `io.dropwizard.Application` → `io.dropwizard.core.Application`, `io.dropwizard.setup.Environment` → `io.dropwizard.core.setup.Environment`, and similar for `Configuration` and `Bootstrap`. `TexeraWebApplication`, `ComputingUnitMaster`, `TexeraWebConfiguration.java`, and `JwtAuth.scala` all reference the old packages.

Mostly IDE-driven find / replace, compile-error-driven cleanup. Volume is large, semantic risk is low — but should be its own commit so reviewers can scan it without mixing in behavior changes.

Part of #5423.

### Task Type

- [x] Refactor / Cleanup