Add support for project view files

In order to limit the scope of what is rendered in the IDE for a given project, implementing support for `.bazelproject` files would help bring this plugin to parity with https://plugins.jetbrains.com/plugin/8609-bazel-for-intellij or https://plugins.jetbrains.com/plugin/22977-bazel-eap-

The spec for bazel project files can be found here: https://ij.bazel.build/docs/project-views.html

Similar to https://github.com/salesforce/bazel-vscode-java and the previously mentioned IntelliJ plugins, adding this feature would also introduce the concept of a project `sync` event that would be triggered by the user. This sync would be responsible for mirroring the state of the current .bazelproject file onto the current vscode workspace.

I would be happy to contribute this feature, but per the contribution guidelines I wanted to file this issue first. Thank you!

Start with the linked `.bazelproject` specification and compare the referenced IntelliJ and bazel-vscode-java implementations. Define how project files scope the VS Code workspace and how a user-triggered sync should mirror the current file; done means the feature reaches parity with the stated project-view behavior.

Written by the indexing model from the issue text.