Performant globbing and background analysis

[skovhus]

When the server boots up we analyze all files matching a glob (default to **/*@(.sh|.inc|.bash|.command)) from the given rootPath. We do this in order to enable features across files (e.g. jump to definition). The current setup works okay for smaller workspaces, but doesn't perform well the rootPath contains too many files. Problems observed:

• globbing (currently using node-glob) can take a very long time to complete!
• we block the LSP server initialisation so the server doesn't respond to other requests
• we can run out of memory and thereby crash the server

This should be fixed in this PR that:

1. switches the globbing library to fast-glob which is a lot faster. Quick benchmarks shows the initial glob resolution to be 10X faster and I didn't find any issues compared to last time this was tried out ([WIP] More file extensions than .sh and shebang lookup #113)
2. limit the amount of bash files we analyse in the background. This is configurable, but defaults to the first 5000 files matching the glob. The background analysis for 500 files takes around 3 seconds to analyze on my machine.
3. we now initialize the server before starting the background parsing

The usefulness of the background analysis for 500 files might be questionable, but the performance is decent IMO. With Sourcing aware symbols completion and jump to definition this will become more interesting.

Resolves #301
Might solve #317, #316 #277