LSP related improvements for Sublime LSP

[soutaro]

Found minor problems when I was testing with Sublime LSP.

• Pass --log-output command line argument to workers so that we can use tail -f for LSP logs
• Delete percentage (55%) message from LSP progress since Sublime LSP prints the percentage itself (Why VSCode doesn't print it...)
• Strip HTML comment from markdown message since Sublime LSP doesn't handle them
• Filter Goto definition results from workers (VSCode automatically de-dup the list, but Sublime LSP doesn't)
• Fix RBS type name completion insertion duplication