feat: specify mapping options via setup()

[willruggiano]

because I want to do (re: my dots):

require("dbee").setup {
    ...
    editor = {
      mappings = {
        run_selection = {
          key = "<C-M>",
          mode = "x",
          opts = {
            expr = true,
          },
        },
      },
    },
    ...
  }

[kndndrj]

thank you for the pr! However, I'm in the middle of a pretty decent refactor of dbee (currently it's on hold due to life stuff).

But I'll definately take this into consideration then.

[willruggiano]

Sounds good! Looking forward to it

[kndndrj]

this functionality is included in the refactor PR (#55).

Closing.