Added grpc monitoring with reflection api

[singhksandeep25]

Description

• A pull request to add monitoring feature for gRPC services.
• Uses grpcurl to make request to the grpc server
• It works by using grpc reflection api on the server
• If server is on, grpcurl --plaintext localhost:50051 list will list methods on the api, and will have a exit code of 0
• If server if down, grpcurl --plaintext localhost:50051 list will throw an error, and will have a exit code of 1

Fixes #1117

Type of change

• New feature (non-breaking change which adds functionality)

Checklist

• [x] My code follows the style guidelines of this project
• [x] I ran ESLint and other linters for modified files
• [x] I have performed a self-review of my own code and tested it
• [x] I have commented my code, particularly in hard-to-understand areas (including JSDoc for methods)
• [x] My changes generate no new warnings
• [ ] My code needed automated testing. I have added them (this is optional task)

[harryzcy]

@singhksandeep25 'replections' in pull request title is a typo, should be reflection.

[louislam]

Unless there is no choice like Apprise or Cloudlfare Tunnels, please use Node.js library instead of external tool.

As it is not convenient for non-Docker users.

[louislam]

#1964 is implemented with node.js library. I will likely choose #1964. Thanks for your contribution anyway.

[singhksandeep25]

Thanks @louislam. I too had a look at #1964 I personally couldn't find that particular node.js library.

[louislam]

Thanks for your contribution anyway, let's focus on https://github.com/louislam/uptime-kuma/pull/1964.