Add TLS configuration for PostgreSQL

[wxing1292]

What changed?
Add TLS configuration for PostgreSQL.

Why?
Improve security.

How did you test it?

• Make PostgreSQL use TLS

• Make Temporal server use TLS

• Create keys / certs

openssl genrsa -aes256 -out ca-key.pem 4096
openssl req -new -x509 -days 365 -key ca-key.pem -sha256 -out ca.pem

openssl genrsa -out server-key.pem 4096
openssl req -subj "/CN=localhost" -sha256 -new -key server-key.pem -out server.csr
openssl x509 -req -days 365 -sha256 -in server.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial -out server-cert.pem

openssl genrsa -out client-key.pem 4096
openssl req -subj '/CN=localhost' -new -key client-key.pem -out client.csr
openssl x509 -req -days 365 -sha256 -in client.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial -out client-cert.pem

rm -v client.csr server.csr

chmod -v 0400 ca-key.pem server-key.pem client-key.pem 
chmod -v 0444 ca.pem server-cert.pem client-cert.pem

• Config PostgreSQL

pg_hba.conf:

hostssl    all             all             127.0.0.1/32            md5 clientcert=1                                                      
hostssl    all             all             ::1/128            md5 clientcert=1     

postgresql.conf:

ssl = on
ssl_cert_file = '<path to PostgreSQL cert>'
ssl_key_file = '<path to PostgreSQL key>'
ssl_ca_file = '<path to PostgreSQL CA>'

• Config Temporal server

datastores:
    postgres-default:
      sql:
        pluginName: "postgres"
        databaseName: "temporal"
        connectAddr: "127.0.0.1:5432"
        connectProtocol: "tcp"
        user: "temporal"
        password: "temporal"
        maxConns: 20
        maxIdleConns: 20
        maxConnLifetime: "1h"
        tls:
          enabled: true
          certFile: "<path to server cert>"
          keyFile: "<path to server key>"
          caFile: "<path to server CA>"
    postgres-visibility:
      sql:
        pluginName: "postgres"
        databaseName: "temporal_visibility"
        connectAddr: "127.0.0.1:5432"
        connectProtocol: "tcp"
        user: "temporal"
        password: "temporal"
        maxConns: 2
        maxIdleConns: 2
        maxConnLifetime: "1h"
        tls:
          enabled: true
          certFile: "<path to server cert>"
          keyFile: "<path to server key>"
          caFile: "<path to server CA>"

Potential risks
N/A

[underrun]

Possibly also support CaData like we do for cassandra

[wxing1292]

one thing at a time.

this only try to make mysql / postgresql similar in terms of file structure, not changing anything for mysql

[alexshtin]

what is the point of having this as separate const?

[wxing1292]

do you mean this?

const dsnFmt = "%v:%v@%v(%v)/%v"

usually, all string const are defined at the very top