[BUG] Implement mutex lock to handle concurrent ssh sessions

[Bhargab]

Describe the bug:

SSH session details are kept in map which are not safe for concurrent use. So we need to implement a mutex lock or use sync.Map. So when ssh usage is high, server might panic and crash.

Log file / Code snippet / Screenshots:

Scope of issue:

• TRASA codebase
• dashboard
• server
• mobile app
• browser extension
• device agent
• website/docs