Support LSP conditions beyond "extensions" (Dockerfile)

[garrett-hopper]

Would like to be able to configure docker-language-server to run on "Dockerfile", however that won't work in "extensions" array due to lsp/index.ts#L116
Perhaps keep "extensions" array and just special case to filename when no leading .?

[zenibako]

+1 on this. Ideally a glob could be used for conditions instead of just the file extension, in case a file extension is used across multiple frameworks (e.g. Salesforce's Lighting Web Components, which uses .html and .js but wouldn't apply to every project using those extensions).