feat(lsp): add handlers for inlay hints (#23736)

initial support; public API left for a follow-up PR

runtime/lua/vim/lsp/protocol.lua

@@ -641,6 +641,12 @@ function protocol.make_client_capabilities()
       },
     },
     textDocument = {
+      inlayHint = {
+        dynamicRegistration = false,
+        resolveSupport = {
+          properties = {},
+        },
+      },
       semanticTokens = {
         dynamicRegistration = false,
         tokenTypes = {
@@ -853,6 +859,9 @@ function protocol.make_client_capabilities()
         dynamicRegistration = true,
         relativePatternSupport = true,
       },
+      inlayHint = {
+        refreshSupport = true,
+      },
     },
     experimental = nil,
     window = {