Dap types command

[ljluestc]

service/dap: support 'types' command

This PR adds support for the types command in the DAP service, enabling clients (like VS Code) to query the list of available types in the debugged program.

Fixes #3729

Description

The types command is available in the Delve CLI but was missing from the DAP implementation. This change:

• Adds the types command to the list of supported debug commands in service/dap/command.go.
• Implements the types handler in Session which delegates to the underlying debugger's Types method.
• Adds verification tests in service/dap/server_test.go to ensure dlv types returns expected output and handles arguments correctly.

Verification

• Added new test cases in TestEvaluateCommandRequest in service/dap/server_test.go.
• Verified that dlv types returns the list of types.
• Verified that dlv types <regex> filters the list correctly.

[aarzilli]

Needs one more tab of indentation.