refactor: move complex rendering into own modules

## Details

There are a few elements we render that have many options and whose
implementations are getting too long to keep piling them into a single
file. This is the case for:

- headings
- code blocks
- pipe tables

Copy all the rendering logic for these with minimal changes into their
own Lua modules.

A couple of things made this easier, the most important one being
sharing a single collection of `marks` which implements the `add`
method. By passing this instance everywhere we're able to add together
all the `marks` without doing a lot of `vim.list_extend` which gets
pretty hard to manage.

The Parser logic previously added for code blocks and pipe tables has
been moved into the new render modules to keep everything tightly
coupled. This is more practical now since the parsers would previously
be living in the top level `markdown` handler growing it to 1000+ lines.

There's nothing technically wrong with a particularly long file but I
like the ability to keep only necessary things together without having
it live amoung all the other random logic. I might take this to its
conclusion and separate everything into its own module.

Should have no visible impact to users.

Author: MeanderingProgrammer

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 - tables indented and no spaces in cells [#142](https://github.com/MeanderingProgrammer/render-markdown.nvim/issues/142)
   [a3617d6](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/a3617d61fcf4cec623ee6acb48570589d7ddcb03)
+- skip tables with errors [c5f25ef](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/c5f25ef19ed9bb3da4e7d947c5119cf8a6191beb)
+- render table border below delimiter when no rows [631e03e](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/631e03e2cfc153c38327c9cc995f4e7c2bbd9b24)
 
 ## 6.2.0 (2024-08-21)
 

lua/render-markdown/context.lua

@@ -8,6 +8,7 @@ local util = require('render-markdown.util')
 ---@field private bottom integer
 ---@field private conceal? table<integer, [integer, integer][]>
 ---@field private links table<integer, [integer, integer, integer][]>
+---@field last_heading integer
 local Context = {}
 Context.__index = Context
 
@@ -24,6 +25,7 @@ function Context.new(buf, win, offset)
     self.bottom = self:compute_bottom(top, offset)
     self.conceal = nil
     self.links = {}
+    self.last_heading = -1
     return self
 end
 

lua/render-markdown/handler/latex.lua

@@ -43,14 +43,14 @@ function M.parse(root, buf)
         return { { expression, latex.highlight } }
     end, expressions)
 
-    local marks = {}
-    list.add_mark(marks, false, info.start_row, info.start_col, {
+    local marks = list.new_marks()
+    marks:add(false, info.start_row, info.start_col, {
         end_row = info.end_row,
         end_col = info.end_col,
         virt_lines = latex_lines,
         virt_lines_above = true,
     })
-    return marks
+    return marks:get()
 end
 
 return M