Update Codicons to the latest release (0.0.26)

[kumattau]

README.md says

msc prefix holds Microsoft's Codicons 0.0.25 with its 385 icons.

but it looks like a working version between 0.0.25 and 0.0.26 is bundled in the package.
I checked that the bundled font and charmap are different from 0.0.25 and 0.0.26.

Now, the latest Codicons 0.0.26 has been released.
So I think that Codicons should be updated to the latest to fix the incorrect version.

[dalthviz]

Makes sense to me @kumattau 👍

[kumattau]

I will send the PR before the end of the year.

[kumattau]

Thanks for working on it for me!