refactor(vimscript)!: drop ctxget(), ctxpush(), etc #40724

Problem:
This functions are most likely never used in the wild.
- They are redundant with `nvim_get_context` + `nvim_load_context`.
- The "context" concept was never fully developed and hasn't gained
  traction.

Solution:
Drop these vimscript aliases, they are just extra cruft.

runtime/lua/vim/_meta/vimfn.gen.lua

@@ -1333,45 +1333,6 @@ function vim.fn.cosh(expr) end
 --- @return integer
 function vim.fn.count(comp, expr, ic, start) end
 
---- Returns a |Dictionary| representing the |context| at {index}
---- from the top of the |context-stack| (see |context-dict|).
---- If {index} is not given, it is assumed to be 0 (i.e.: top).
----
---- @param index? integer
---- @return table
-function vim.fn.ctxget(index) end
-
---- Pops and restores the |context| at the top of the
---- |context-stack|.
----
---- @return any
-function vim.fn.ctxpop() end
-
---- Pushes the current editor state (|context|) on the
---- |context-stack|.
---- If {types} is given and is a |List| of |String|s, it specifies
---- which |context-types| to include in the pushed context.
---- Otherwise, all context types are included.
----
---- @param types? string[]
---- @return any
-function vim.fn.ctxpush(types) end
-
---- Sets the |context| at {index} from the top of the
---- |context-stack| to that represented by {context}.
---- {context} is a Dictionary with context data (|context-dict|).
---- If {index} is not given, it is assumed to be 0 (i.e.: top).
----
---- @param context table
---- @param index? integer
---- @return integer
-function vim.fn.ctxset(context, index) end
-
---- Returns the size of the |context-stack|.
----
---- @return any
-function vim.fn.ctxsize() end
-
 --- @param lnum integer|string
 --- @param col? integer
 --- @param off? integer