feat: support overriding filetypes for adapters

[chomosuke]

First of all, thank you for this plugin, it greatly reduced my config size.

Use case:
I used simrat39/rust-tools.nvim and would like it to configure my dap instead of mason-nvim-dap.nvim.

Solution:
This PR allow me to do things like:

require('mason-nvim-dap').setup {
  automatic_setup = { filetypes = { codelldb = { 'c', 'cpp' } } },
}

This way I don't have to override the entire handler for codelldb and still let mason-nvim-dap.nvim configure c and cpp for me.