Remove .ijwb and .idea, migrate to import_run_configurations

The Bazel IntelliJ team has stated that while checking in the .ijwb folder
technically sorta-kinda works, they recommend against it since they cannot
guarantee any kind of backwards compatibility. Indeed, bootstrapping a
working IDE project from a clean checkout with .ijwb has been a
delicate matter in the past and is currently broken again.

Do the supported thing instead and nuke .ijwb and .idea and ignore them.
The .bazelproject file can then be used to create a new project using
File → Import Bazel project, creating the workspace from scratch.

Run configurations are now created by the Bazel plugin, and those XML
files come with a backwards compatibility promise.

This means that we lose all other shared settings except run
configurations. If there's particular configs that we want to keep, we
need to write custom tooling which mangles the XML configs, which will
allows us to deal with backwards compatibility and differences in
developer setups (i.e. outside contributors).

Test Plan:
Cloned the project from scratch, imported the Bazel
project, everything worked on the first try :O

X-Origin-Diff: phab/D658
GitOrigin-RevId: 979ac5345fd8a5f26a5f8ec3d5882ea477b48a69
diff --git a/.bazelproject b/.bazelproject
new file mode 100644
index 0000000..7fac025
--- /dev/null
+++ b/.bazelproject
@@ -0,0 +1,34 @@
+directories:
+  # Add the directories you want added as source here
+  # By default, we've added your entire workspace ('.')
+  .
+
+# Automatically includes all relevant targets under the 'directories' above
+derive_targets_from_directories: false
+
+targets:
+  # If source code isn't resolving, add additional targets that compile it here
+  //...
+
+additional_languages:
+  # Uncomment any additional languages you want supported
+  # android
+  # dart
+  go
+  # javascript
+  # kotlin
+  # python
+  # scala
+  # typescript
+
+import_run_configurations:
+  intellij/run/Connect_to_dlv_on__2345.xml
+
+  intellij/run/e2e_test.xml
+  intellij/run/e2e_test_in_dbg_mode.xml
+  intellij/run/e2e_test_in_dbg_mode_with_dlv.xml
+
+  intellij/run/Run_all_tests.xml
+
+  intellij/run/Run_single_node_cluster.xml
+  intellij/run/Run_single_node_cluster_in_dbg_mode.xml