This allows us to support opening a single file in multiple
language server instances.
This can be useful when combining for example a latex and a language
tool language server.

Using the new latex lexer from the upcoming vis release I noticed
that vis-lspc default style id 43 overrides the environment style
from the lexer.

To prevent id clashing use the highest allowed id for lexer styles,
which is 64 according to the enum defined in vis/ui.h.

Send language server settings after initialization via a
workspace/didChangeConfiguration notification.

Implement a workspace/configuration handler using the values stored
in the language server settings.

Send the init_options as initializationOptions in the initialize
parameters.

Fixes 3e1894cd0825e028c9e37c90f8dbaa8499fdd4e3.