Support installation of clangd binaries if not found.

[sam-mccall]

Also has auto-update checks, but turned off by default for now.

See:

• Library with main logic: clangd/node-clangd@3ce82ac
• PR for vscode-clangd: Support installation of clangd server. vscode-clangd#5

[hokein]

thanks, looks good from my side.

[fannheyward]

I make two small commits:

1. @clangd/install as devDependencies, this will bundle all dependencies by webpack, to a single lib/index.js file.
2. run editor.action.restart after download, no more :CocRestart needed.

[oblitum]

Just missed an update to README which states this is not supported.

[oblitum]

Will this grab clangd from prereleases as well or just releases?

Another question is if I enable this will it override my system installation correctly (since clangd comes bundled to clang)?

[fannheyward]

@oblitum just latest release clangd/node-clangd@3ce82ac#diff-f41e9d04a45c83f3b6f6e630f10117feR146

[oblitum]

@fannheyward ah, ok, thanks!

[fannheyward]

@sam-mccall @hokein this will update clangd.path in coc-settings.json?

[sam-mccall]

@fannheyward Thanks! LGTM

this will update clangd.path in coc-settings.json?

Correct, it'll install a portable clangd (just unzip the release) under ~/.config/coc/extensions/coc-clangd-data/install/, and then update coc's clangd.path setting to point to it. The rest of the system is not affected.