ggml webgpu: unary op suppport, code refactoring, ops support

[reeselevine]

This PR adds the following for the WebGPU backend:

• Basic support for most unary operators
  • Updates the wgsl shader generation script to handle formatting functions for different unary operators
• Refactoring the webgpu backend code a bit
  • Moves pipeline initialization/storage to use std::map instead of statically sized arrays, since not all combinations of features (inplace,vectorized, etc) are needed/used.
  • Adds helper functions, e.g. CEIL_DIV, for common calculations to the webgpu backend file
• Finally adds WebGPU backend operator support to ops.md

I know this PR is large, all of the code is contained to the WebGPU backend though. This code was also partially written by @abhijitramesh, @XXjcontiniXX, and @neha-ha, and I have reviewed their code.

[CISC]

Suggested change

	def replace_repl_placeholders(variant, template_map):
	for repl, code in variant["REPLS"].items():
	for key, val in template_map.items():
	# Match "key" and avoid matching subsequences using by using \b
	code = re.sub(rf'\b{re.escape(str(key))}\b', str(val), code)
	variant["REPLS"][repl] = code
	return variant
	def replace_placeholders(shader_text, replacements):
	def replace_repl_placeholders(variant, template_map):
	for repl, code in variant["REPLS"].items():
	for key, val in template_map.items():
	# Match "key" and avoid matching subsequences using by using \b
	code = re.sub(rf'\b{re.escape(str(key))}\b', str(val), code)
	variant["REPLS"][repl] = code
	return variant
	def replace_placeholders(shader_text, replacements):