feat(healthcheck): support native lua healthchecks, and fixes

After neovim/neovim#15259 lua healthchecks are called directly and are
prefered over neovim autoload ones. The discover of Lua ones requires
the function to be named "check()".

Also the mentioned PR changed the design of healthchecks to not use
output capturing, therefore avoid printing and instead concatenate and
call the health functions.

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -41,7 +41,7 @@ body:
 
   - type: textarea
     attributes:
-      label: Output of `:checkhealth nvim_treesitter`
+      label: Output of `:checkhealth nvim-treesitter`
       render: markdown
     validations:
       required: true

autoload/health/nvim_treesitter.vim

@@ -1,3 +1,3 @@
 function! health#nvim_treesitter#check()
-  lua require 'nvim-treesitter.health'.checkhealth()
+  lua require 'nvim-treesitter.health'.check()
 endfunction

lua/nvim-treesitter/health.lua

@@ -109,17 +109,17 @@ local function query_status(lang, query_group)
   end
 end
 
-function M.checkhealth()
+function M.check()
   local error_collection = {}
   -- Installation dependency checks
   install_health()
   queries.invalidate_query_cache()
-  health_start "Parser/Features H L F I J"
   -- Parser installation checks
+  local parser_installation = { "Parser/Features H L F I J" }
   for _, parser_name in pairs(info.installed_parsers()) do
     local installed = #api.nvim_get_runtime_file("parser/" .. parser_name .. ".so", false)
 
-    -- Only print informations about installed parsers
+    -- Only append information about installed parsers
     if installed >= 1 then
       local multiple_parsers = installed > 1 and "+" or ""
       local out = "  - " .. parser_name .. multiple_parsers .. string.rep(" ", 15 - (#parser_name + #multiple_parsers))
@@ -130,16 +130,19 @@ function M.checkhealth()
           table.insert(error_collection, { parser_name, query_group, err })
         end
       end
-      print(out)
+      table.insert(parser_installation, out)
     end
   end
-  print [[
+  local legend = [[
 
- Legend: H[ighlight], L[ocals], F[olds], I[ndents], In[j]ections
+  Legend: H[ighlight], L[ocals], F[olds], I[ndents], In[j]ections
          +) multiple parsers found, only one will be used
          x) errors found in the query, try to run :TSUpdate {lang}]]
+  table.insert(parser_installation, legend)
+  -- Finally call the report function
+  health_start(table.concat(parser_installation, "\n"))
   if #error_collection > 0 then
-    print "\nThe following errors have been detected:"
+    health_start "The following errors have been detected:"
     for _, p in ipairs(error_collection) do
       local lang, type, err = unpack(p)
       health_error(lang .. "(" .. type .. "): " .. err)