[FEATURE] Allow specifying a custom path for `vhdl_ls.toml`

[nselvara]

Description

Hi there,

I have a repository with multiple folders, each containing its own vhdl_ls.toml file. However, VHDL-LS currently only looks in predefined workspace paths and loads the toml file from there.

I would like the ability to manually specify the path to the configuration file, allowing more flexibility in structuring projects. For now, even a simple option to define a single path manually would be very helpful.

I also came across this issue, which discusses adding support for multiple files. While that would be useful, my main request is just the ability to specify a single path for now.

Thanks for considering this feature!