Move security BBEs to new-examples directory and reorganize

[ldclakmal]

Purpose

$subject was done for following BBEs:

REST API Security

• Service - Basic Auth File User Store
• Service - Basic Auth LDAP User Store
• Service - JWT Auth
• Service - OAuth2
• Client - Basic Auth
• Client - Bearer Token Auth
• Client - Self Signed JWT Auth
• Client - OAuth2 Client Credentials Grant Type
• Client - OAuth2 Password Grant Type
• Client - OAuth2 Refresh Token Grant Type
• Service - SSL/TLS
• Client - SSL/TLS
• Service - Mutual SSL
• Client - Mutual SSL

Security

• Cryptographic Operations
• JWT Issue/Validate

URL

• URL Encode/Decode Operations

Related to ballerina-platform/ballerina-library#584

[shafreenAnfar]

I think we can organize these BBEs a bit.