[Refactor] DCR Monitor Refactoring (2/N) (#19)

2/N PR for a major refactoring of DCR Monitor. See #15.

1/N: #16

# Changes

* Remove "UpdateJobStatus" endpoint from the API. Everything must be
handled in the reconciler instead.
* Added `imagebuilder` interface, which currently has one image builder
implementation which is Kaniko
* Moved `RunJob` logic into the reconciler. Now TEE is launched by the
reconciler via `LaunchInstance` method in `TEEProvider`.
* Removed bunch of shallow interfaces from `Config`. Removed bunch of
unnecessary global configs, and made them local.
* Completely removed KMS logic. We don't need user keys and
stage1/stage2 keys in the open source version
* Completely removed `PrepareResourcesForUser`. Any logic needed for TEE
should go to `TEEProvider`.
* Removed `project_number` from config, because it is not needed
anymore.
* Removed logic for creating/updating workload identity pool provider.
It's not used any longer so let's revisit later when we implement data
confidentiality.
  
# Caveat

* This still doesn't support getting attestation report.

# Testing

Added unit tests, and also did manual end-to-end testing.

Author: dayeol

.env.example

@@ -2,6 +2,5 @@ env=""
 mysql_username=""
 mysql_password=""
 project_id=""
-project_number=""
 region=""
 zone=""

BUILD

@@ -4,7 +4,6 @@ load(
     "//:config.bzl",
     "deploy_env",
     "gcp_project_id",
-    "gcp_project_number",
     "gcp_region",
     "gcp_zone",
     "registry_api_image",
@@ -20,7 +19,6 @@ sh_binary(
     srcs = [":generate_app_config_file.sh"],
     args = [
         gcp_project_id,
-        gcp_project_number,
         deploy_env,
         gcp_region,
         gcp_zone,
@@ -31,9 +29,8 @@ genrule(
     name = "generate_app_config",
     srcs = [],
     outs = ["config.yaml"],
-    cmd = "$(location :generate_app_config_sh) {} {} {} {} {} > $(OUTS)".format(
+    cmd = "$(location :generate_app_config_sh) {} {} {} {} > $(OUTS)".format(
         gcp_project_id,
-        gcp_project_number,
         deploy_env,
         gcp_region,
         gcp_zone,

README.md

@@ -88,7 +88,6 @@ env="dev"                        # the deployment environment
 mysql_username="mockname"        # mysql database username 
 mysql_password="mockpwd"         # mysql database password
 project_id="you project id"      # gcp project id
-project_number="1310xxxx092"     # gcp project number
 region=""                        # the region that the resources created in
 zone=""                          # the zone that the resources created in
 ```