fix: trim connection strings to ensure valid inputs

[tnaum-ms]

This pull request trims user input when connection string is provided + it adds validation to ensure that the connection string is not empty when creating a new connection. If the user attempts to submit an empty connection string, a localized error message is shown.

Validation improvements:

• Added a check in PromptConnectionStringStep.ts to trim and validate that the connection string is not empty, returning a localized error if it is.
• Added the localized string "Connection string cannot be empty." to bundle.l10n.json for use in error messaging.

[Copilot]

Pull request overview

This pull request adds validation to ensure that connection strings provided by users are trimmed and not empty when creating a new MongoDB connection. The change prevents users from submitting whitespace-only or empty connection strings.

Changes:

• Added empty string validation in the async validator to match the established pattern used throughout the codebase
• Trimmed user input before validation to handle leading/trailing whitespace
• Added a localized error message for empty connection strings

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/commands/newConnection/PromptConnectionStringStep.ts	Added trimming and empty string validation to the validateConnectionString method to ensure valid connection string input
l10n/bundle.l10n.json	Added localized error message "Connection string cannot be empty." for the new validation