Respect global .gitignore when searching

[vanossj]

The global .gitignore file, aka git config core.excludesfile setting should be used when searching, just like the local .gitignore file is.

Currently files/folders will be ignored if they are in the local .gitignore, but not if they are only in the global git ignore.

#49239 asked about this feature, but it was incorrectly closed.

[vscodebot]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• Git ignore decorations do not reload when branch is changed (#53260)
• Git: Support to automatically add large folders to .gitignore (#44304)

[roblourens]

I can add a setting to be opted into this, but I disabled it by default because it confused too many people

[roblourens]

Would take a PR that adds a setting, false by default, for whether to add this flag: https://github.com/Microsoft/vscode/blob/master/src/vs/workbench/services/search/node/ripgrepTextSearch.ts#L514

[skprabhanjan]

@roblourens , can i send a PR on this?
I have added a new config in the interface IRawSearch (https://github.com/Microsoft/vscode/blob/master/src/vs/workbench/services/search/node/search.ts#L22) and used that while pushing it to args, but can you help me understand if by adding
ignoreGlobal?: boolean; , will it also make the default value as false?
Thanks :)