Add support to retrieve the location of the cursor

Thank you for building the JetBrains MCP plugin! I am a developer working on https://ampcode.com and this plugin has been invaluable for our users so far.

I am trying to integrate the JetBrains MCP server more deeply with Amp and one of the key missing pieces of information is the current location of the cursor (ideally as a line/column, 0-based or 1-based). I can get the selected text contents, which helps a lot. However, often the user won't have selected any text but they still expect Amp to understand where their cursor location is.