Add env variables for make dev target

[john-david3]

Proposed changes

• Added two environment variables to the make dev target
  • One for the manifest file directory path and the other for the collector config path
• Created new default value for the manifest directory
• Removed the manifest file path from file_manager_service.go

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING document
• I have run make install-tools and have attached any dependency changes to this pull request
• If applicable, I have added tests that prove my fix is effective or that my feature works
• If applicable, I have checked that any relevant tests pass after adding my changes
• If applicable, I have updated any relevant documentation (README.md)
• If applicable, I have tested my cross-platform changes on Ubuntu 22, Redhat 8, SUSE 15 and FreeBSD 13

[dhurley]

Suggested change

	COLLECTOR_CONFIG_PATH=$(COLLECTOR_PATH) MANIFEST_DIR_PATH=$(MANIFEST_DIR) $(GORUN) -ldflags=$(DEBUG_LDFLAGS) $(PROJECT_DIR)/$(PROJECT_FILE)
	NGINX_AGENT_COLLECTOR_CONFIG_PATH=$(COLLECTOR_PATH) NGINX_AGENT_MANIFEST_DIR_PATH=$(MANIFEST_DIR) $(GORUN) -ldflags=$(DEBUG_LDFLAGS) $(PROJECT_DIR)/$(PROJECT_FILE)

Shouldn't the env variables have the NGINX_AGENT_ prefix?

[john-david3]

I might be wrong, but does viper not do this automatically in the registerFlags method in config.go:

viperInstance.SetEnvPrefix(EnvPrefix)