Add more linters to improve code readability (#19989)

Add nakedret, unconvert, wastedassign, stylecheck and nolintlint linters to improve code readability

- nakedret - https://github.com/alexkohler/nakedret - nakedret is a Go static analysis tool to find naked returns in functions greater than a specified function length.
- unconvert - https://github.com/mdempsky/unconvert - Remove unnecessary type conversions
- wastedassign - https://github.com/sanposhiho/wastedassign -  wastedassign finds wasted assignment statements.
- notlintlint -  Reports ill-formed or insufficient nolint directives
- stylecheck - https://staticcheck.io/docs/checks/#ST - keep style consistent
  - excluded: [ST1003 - Poorly chosen identifier](https://staticcheck.io/docs/checks/#ST1003) and [ST1005 - Incorrectly formatted error string](https://staticcheck.io/docs/checks/#ST1005)

modules/activitypub/client.go

@@ -92,7 +92,7 @@ func NewClient(user *user_model.User, pubID string) (c *Client, err error) {
 		priv:        privParsed,
 		pubID:       pubID,
 	}
-	return
+	return c, err
 }
 
 // NewRequest function
@@ -110,7 +110,7 @@ func (c *Client) NewRequest(b []byte, to string) (req *http.Request, err error)
 		return
 	}
 	err = signer.SignRequest(c.priv, c.pubID, req, b)
-	return
+	return req, err
 }
 
 // Post function
@@ -120,5 +120,5 @@ func (c *Client) Post(b []byte, to string) (resp *http.Response, err error) {
 		return
 	}
 	resp, err = c.client.Do(req)
-	return
+	return resp, err
 }