[clangd] Enable folding ranges by default.

[Trass3r]

Whenever I tried this option in the past it crashed clangd.
I recommend doing some more testing before flipping the switch.

[kadircet]

clang-tools-extra/clangd/tool/ClangdMain.cpp

340

i think we should just retire the flag altogether, ATM this is only preventing clangdlspserver from announcing the capability.

the only benefit of keeping it as a flag is, we can turn it off quickly if its crashing constantly. but we should fix those crashes instead. so do you mind:

• moving it to be near other retiredflags (around line 320)
• always announce foldingrangeprovider capability and bind the method in clangdlspserver.cpp
• get rid of the option inside clangdserver.h

[kadircet]

In D132919#3757685, @Trass3r wrote:

Whenever I tried this option in the past it crashed clangd.
I recommend doing some more testing before flipping the switch.

we've a new implementation of folding ranges based on pseudo parsing now. hence no more crashes 🎉

[usaxena95]

Addressed comments.

[kadircet]

thanks, lgtm!

clang-tools-extra/clangd/tool/ClangdMain.cpp

list<std::string> TweakList{
     Hidden,
     CommaSeparated,
 };
 
 opt<bool> FoldingRanges{
     "folding-ranges",
     cat(Features),
     desc("Enable preview of FoldingRanges feature"),
-    init(false),
+    init(true),
     Hidden,
 };
 
 opt<unsigned> WorkerThreadsCount{
     "j",
     cat(Misc),
     desc("Number of async workers used by clangd. Background index also "
          "uses this many workers."),