hm: option for default linking method

[Misterio77]

Hi all!

Here's a (slightly late) follow up to #99.

This adds an option that allows users to change the default linking method.

Bindfs has been bothering me with the performance hits, and writing method = symlink for every entry is cumbersome. The default still is bindfs, so no breaking changes.

To make this implementation cleaner, I also refactored the directory type to use coercedTo (in its own commit, to be easier to review).

[Misterio77]

Can confirm there are no diffs in my home path when running this branch versus the main branch

[maxbfuer]

I've been using this PR for about a week now and everything is working great on my end. Thank you both for your work on this PR and project :)

[talyz]

Thanks a lot for your work on this! Looks great! Just some minor comments.

[fbuchlak]

Hi @talyz @Misterio77 Don't want to necrobump, but is there something except minor comments blocking this PR? This feature would be handy.

[Misterio77]

Hey, sorry for the delay! Got quite busy last semester. Will see if I can get this going.

[Misterio77]

Should be good to go!

CC @talyz @fbuchlak

[Misterio77]

Oops sorry, hold on a bit. Got some eval errors after rebasing.

Nevermind, was an error in my own config. This PR should be good.

[talyz]

Thanks!

[eyJhb]

@Misterio77 thanks for this PR, I REALLY appreciate it. I've just been patching impermanence for a long while, instead of doing it properly. Thanks for the effort! :)