fix: instruct models not to generate passwords for createDBUser

[nirinchev]

While testing, noticed that models will generate overly simplistic passwords with the atlas-create-db-user tool, which is not ideal. This changes the args description to instruct the model not to attempt generating a password and instead we're generating one.

[Copilot]

Pull Request Overview

This PR refines the password handling for the database user creation tool by instructing models not to generate passwords and instead relying on a secure password generator if one isn’t supplied.

• Updated tests to verify both supplied and generated password flows.
• Removed redundant password generation code from connectCluster in favor of a common utility.
• Modified argument description and success message in createDBUser tool to clearly communicate password handling.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/integration/tools/atlas/dbUsers.test.ts	Updates test cases and assertions to account for generated password output.
tests/integration/helpers.ts	Replaces Array.isArray check with the toBeArray matcher for improved readability.
src/tools/atlas/metadata/connectCluster.ts	Removes redundant secure password generation in favor of a centralized utility.
src/tools/atlas/create/createDBUser.ts	Adjusts argument descriptions and conditional logic for password generation, updating the success message accordingly.
src/common/atlas/generatePassword.ts	Introduces a new secure password generator utility using crypto.

Comments suppressed due to low confidence (1)

src/tools/atlas/create/createDBUser.ts:83

• The success message contains a spelling error; 'sucessfully' should be corrected to 'successfully'.

text: `User "${username}" created sucessfully${shouldGeneratePassword ? ` with password: `${password}` : ""}.`,