Make adjustment to use vector function rather than vector literal

[thatnerdjosh]

Based on comment in #82

[thatnerdjosh]

@factyy @yyoncho - made changes as per Wilfred's comment in the issue regarding the ht usage.

[factyy]

@yyoncho @thatnerdjosh , thanks! Merged now

[sfavazza]

There is still a problem with the vector definition in the mapping, the hash-table is not evaluated. To test, try running this in a project:
(lsp-docker-get-path-mappings lsp-docker-persistent-default-config (lsp-workspace-root))

You should get the error: Wrong type argument: hash-table-p, (ht ('source ".") ('destination "/projects"))

I guess this is due to how vectors are defined in elisp, from the manual:

A vector, like a string or a number, is considered a constant for evaluation: the result of evaluating it is the same vector. This does not evaluate or even examine the elements of the vector.