feat: add post commenting feature

[Pantani]

Description

add post commenting feature to the x/blog moduleL

• Add a new Msg service method called CreateComment. This method's input takes:
  • post_slug as string,
  • author as string (Bech32-encoded address),
  • body as a string.
• New comments are persisted in the blockchain state. Comment cannot be inserted into the state if its corresponding Post does not exist in the state.
• Add a new AllComments gRPC query method. This method's input should take a post_slug (a string) and returns all the comments on a post.
• Add CLI subcommands, tx create-comment and query list-comments, which call the CreateComment and AllComments service methods under the hood.

Aditional features

• A comment cannot be duplicated by the same user to avoid flooding the posts or the network.
• Add config.yml for we can run the chain using ignite (eg: ignite c serve);

How to test

Run the chain:

• Using the Makefile:

$ make build

• Using the Ignite CLI

$ ignite c serve

Test Commands:

• Create posts:

$ becd tx blog create-post cosmos1ezptsm3npn54qx9vvpah4nymre59ykr9967vj9 slug1 title1 body1 --chain-id bec
$ becd tx blog create-post cosmos1ezptsm3npn54qx9vvpah4nymre59ykr9967vj9 slug2 title2 body2 --chain-id bec

• Query posts:

$ becd q blog list-post

• Create comments for the first post (slug1)

$ becd tx blog create-comment cosmos1ezptsm3npn54qx9vvpah4nymre59ykr9967vj9 slug1 body1-1 --chain-id bec 
$ becd tx blog create-comment cosmos1ezptsm3npn54qx9vvpah4nymre59ykr9967vj9 slug1 body1-2 --chain-id bec 
$ becd tx blog create-comment cosmos1ezptsm3npn54qx9vvpah4nymre59ykr9967vj9 slug1 body1-3 --chain-id bec 
$ becd tx blog create-comment cosmos1ezptsm3npn54qx9vvpah4nymre59ykr9967vj9 slug1 body1-4 --chain-id bec 

• Query the comments

$ becd q blog list-comment slug1

• Create comments for the second post (slug2), the last one was duplicated from the last

$ becd tx blog create-comment cosmos1ezptsm3npn54qx9vvpah4nymre59ykr9967vj9 slug2 body2-1 --chain-id bec 
$ becd tx blog create-comment cosmos1ezptsm3npn54qx9vvpah4nymre59ykr9967vj9 slug2 body2-2 --chain-id bec 
$ becd tx blog create-comment cosmos1ezptsm3npn54qx9vvpah4nymre59ykr9967vj9 slug2 body2-2 --chain-id bec 

• Query the comments. You should see only two comments

$ becd q blog list-comment slug2

• Try to create a comment for a invalid post slug

$ becd tx blog create-comment cosmos1ezptsm3npn54qx9vvpah4nymre59ykr9967vj9 invalidSlug bodyIn --chain-id bec 

• The post should not exist

$ becd q blog list-comment invalidSlug