Bug: Removing ' and ` marks throws errors.

[davinosuke]

I have just started to use this plugin, and I stumbled upon this accidentally.

I somehow managed to explicitly set a ` mark, and when I tried to remove it with dm`, I got this error message:

E5108: Error executing lua: vim/_editor.lua:0: nvim_exec2(), line 1: Vim(delmarks):E475: Invalid argument: `
stack traceback:
        [C]: in function 'nvim_exec2'
        vim/_editor.lua: in function 'cmd'
        ...vid/.local/share/nvim/lazy/marks.nvim/lua/marks/mark.lua:110: in function 'delete_mark'
        ...vid/.local/share/nvim/lazy/marks.nvim/lua/marks/init.lua:43: in function <...~.local/share/nvim/lazy/marks.nvim/lua/marks/ini
t.lua:34>

The only relevant setting I have enabled is the keymapping [toggle = "mm"], and when I use it, I get a similar message:

E5108: Error executing lua: vim/_editor.lua:0: nvim_exec2(), line 1: Vim(delmarks):E475: Invalid argument: `
stack traceback:
        [C]: in function 'nvim_exec2'
        vim/_editor.lua: in function 'cmd'
        ...vid/.local/share/nvim/lazy/marks.nvim/lua/marks/mark.lua:110: in function 'delete_mark'
        ...vid/.local/share/nvim/lazy/marks.nvim/lua/marks/mark.lua:138: in function 'delete_line_marks'
        ...vid/.local/share/nvim/lazy/marks.nvim/lua/marks/mark.lua:147: in function 'toggle_mark_cursor'
        ...vid/.local/share/nvim/lazy/marks.nvim/lua/marks/init.lua:30: in function <...~/.local/share/nvim/lazy/marks.nvim/lua/marks/ini
t.lua:28>

I get similar errors on ' and " marks as well.
Yes, I know they are special builtin marks, but you can also set and remove them manually (kind of).
Note that the marks do get removed, they just display the error messages, too.

[shaksiper]

This is becuase ` and ' essentially same mark:

:h mark-motions

Jumping to a mark can be done in two ways:

1. With ` (backtick): The cursor is positioned at the specified location
   and the motion is |exclusive|.
2. With ' (single quote): The cursor is positioned on the first non-blank
   character in the line of the specified location and
   the motion is linewise.

and you cannot delete ' mark manually.
and on the same page:

:delm[arks] {marks} Delete the specified marks. Marks that can be deleted
include A-Z and 0-9. You cannot delete the ' mark.
They can be specified by giving the list of mark
names, or with a range, separated with a dash. Spaces
are ignored. Examples: >
emphasis is mine.

But I think " should work but fails with the same error message, my gut says it is related to escaping, but I might be wrong.

Ideally we should escape it and if the mark cannot be deleted it should tell so.