Upgrade language server to 0.1.0

[rcjsuen]

This update provides the following changes:

• continued improvements and fixes to the semantic tokens parser (Request textDocument/semanticTokens failed #2055)
• editor visuals for the deprecated MAINTAINER instruction
• linting fixes due to incorrect calculations of ranges
• navigation of build stages (Ctrl Click on FROM leads to a DockerHub link, instead of a stage in a multi-stage config #2043)

Please use the Dockerfile to test the new changes and bug fixes.

FROM alpine AS base
# this should not be a link anymore, issue 2043
# instead, clicking on it now should jump to the stage definition above
# https://github.com/microsoft/vscode-docker/issues/2043
FROM base
# this will now have a strikeout decoration to indicate that it is deprecated
# not sure if this is only for VS Code 1.47 or not though...?
MAINTAINER user

# the A should be coloured like X and Y
RUN --mount=X=Y,A echo

FROM scratch
# this should create an error because the ENV has no arguments
ENV \
    # comment

The following Dockerfiles have very specific whitespace characters to reproduce the error in question. Simply copy and paste the content into a Dockerfile and and open the Output panel and select the Dockerfile Language Server to verify that there are no errors being logged. Do not save the file as the formatter will change the integrity of the file.

# issue 2055
# https://github.com/microsoft/vscode-docker/issues/2055
FROM alpine
ENV \
    # common variables:
    ENV1=something

FROM alpine
COPY a b \
\ 
/dir

# there are two problems here
# 1 - the semantic tokens is buggy and there is an infinite loop here
# 2 - the validation is wrong, the red squiggles should be over the whole argument
# which spans across all 3 lines instead of simply the `/di\` in the beginning
FROM alpine
COPY a b /di\
\
\r

[rcjsuen]

Looks like the macOS build failed but I have no idea why.

[bwateratmsft]

The macOS pipeline is really temperamental for whatever reason...

[bwateratmsft]

Awesome as usual, thanks @rcjsuen!

[rcjsuen]

@bwateratmsft Thanks for reviewing. See you again in a month or two I guess...? :P