Support slash in layer ID

[keichan34]

Description

Fix #56 by creating directories recursively after joining the layers directory with the layer ID. Before this fix, the layers directory was being created, but if the ID contained a slash, it would try to write the file to an nonexistent directory, resulting in an error.

Type of Pull Request

• Adding a feature
• Fixing a bug
• Maintaining documents
• Others ()

Verify the followings

• Code is up-to-date with the main branch
• No build errors after npm run build
• No lint errors after npm run lint
• No errors on using charites help globally
• Make sure all the exsiting features working well
• Have you added at least one unit test if you are going to add new feature?
• Have you updated documentation?

Refer to CONTRIBUTING.MD for more details.

[hfu]

I like this implementation although I am not really sure this works perfectly in Windows environments ;-)

[ubukawa]

Dear @keichan34 ,
Thank you very much for this improvement! I really appreciate it.
(I am sorry for my late response!)

[keichan34]

@hfu Ah, that's a good point. If the name of the file isn't stable between UNIX and Windows operating systems, charites projects won't be able to shared between them. I'll double check what happens on Windows and make fixes as necessary. Thanks!

[ubukawa]

Just for your information. I tried this on a docker container. This is really wonderful.
We can beautifully import JSON style into a series of sub-directory.
https://github.com/ubukawa/cmv-test/tree/main/esri/layers

We can have a long name for a style layer.
When building a JSON style, I found that there would be an error if we use ">(「折り返し形式のブロックスカラー」)" in the layers where we use "!!inc/file"

I wonder we may need to avoid using ">". This is not directly related to this PR, I will share it at issue.]