feat(treesitter/extmark): support removing a conceal highlight #35087

Problem:
Cannot remove a `@conceal` highlight when defined in highlights.scm.

Solution:
Support a `@noconceal` highlight that works similarly to `@nospell` where it
overrides the conceal set on the range to remove it. Additionally, can
set the conceal metadata field to false for the same behavior.

runtime/lua/vim/treesitter/query.lua

@@ -609,7 +609,7 @@ predicate_handlers['any-vim-match?'] = predicate_handlers['any-match?']
 ---@class vim.treesitter.query.TSMetadata
 ---@field range? Range
 ---@field offset? Range4
----@field conceal? string
+---@field conceal? string|boolean
 ---@field bo.commentstring? string
 ---@field [integer]? vim.treesitter.query.TSMetadata
 ---@field [string]? integer|string