Auto merge of #3339 - micbou:update-ycmd, r=Valloric

[READY] Update ycmd

Include the following changes:

 - PR ycm-core/ycmd#1180: trigger semantic completion when instructed by server;
 - PR ycm-core/ycmd#1184: simplify LSP completer API for starting server;
 - PR ycm-core/ycmd#1187: improve Clangd completer initialization;
 - PR ycm-core/ycmd#1191: ease Clangd completer initialization;
 - PR ycm-core/ycmd#1193: fix system header search paths on macOS for Objective-C++;
 - PR ycm-core/ycmd#1194: update Jedi to 0.13.3 and Parso to 0.3.4;
 - PR ycm-core/ycmd#1195: ignore identifiers returned by TSServer in JavaScript;
 - PR ycm-core/ycmd#1196: update TSServer to 3.3.3333;
 - PR ycm-core/ycmd#1197: support -B flag in C-family languages.

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