Remove unnecessary argument from lsp_symbol_rename command

[jwortmann]

I saw that this command has two arguments position and point, with one of them being unnecessary. Currently position is just an internal argument used to pass it to itself when the command is re-triggered after prepareRename response. It seems that position existed before point was added (to LspTextCommand), but now we can use point for that instead. The logic should be completely unaffected by this change, and the line with location = ... (105) can be simplified because get_position also prefers point if given.