h264: full SPS parsing

[mildsunrise]

Please review #252 first, as it's a dependency for this PR.

Extends H264SeqParameterSet to parse the full descriptor (right now it's not parsing the VUI).

I've basically adapted the code from nal-extractor:
https://github.com/medooze/nal-extractor/blob/main/lib/SPS.ts
https://github.com/medooze/nal-extractor/blob/main/test/SPS.test.ts

output for:

64001eacb2010020f3cf80b5060606a50000030001000003003c9f162e48

is:

[H264SeqParameterSet
	profile_idc=64
	constraint_set0_flag=0
	constraint_set1_flag=0
	constraint_set2_flag=0
	reserved_zero_5bits=0
	level_idc=1e
	seq_parameter_set_id=0
	log2_max_frame_num_minus4=0
	pic_order_cnt_type=2
	log2_max_pic_order_cnt_lsb_minus4=0
	delta_pic_order_always_zero_flag=0
	offset_for_non_ref_pic=0
	offset_for_top_to_bottom_field=0
	num_ref_frames_in_pic_order_cnt_cycle=0
	num_ref_frames=3
	gaps_in_frame_num_value_allowed_flag=0
	pic_width_in_mbs_minus1=31
	pic_height_in_map_units_minus1=31
	frame_mbs_only_flag=1
	mb_adaptive_frame_field_flag=0
	direct_8x8_inference_flag=1
	frame_crop=[
		left_offset=0
		right_offset=6
		top_offset=0
		bottom_offset=6
	]
	vui_parameters=[
		aspect_ratio_info=[
			aspect_ratio_idc=1
		]
		overscan_info=[
			<Not present>
		]
		video_signal_type=[
			video_format=5
			video_full_range_flag=0
			colour_description=[
				colour_primaries=6
				transfer_characteristics=6
				matrix_coefficients=6
			]
		]
		chroma_loc_info=[
			type_top_field=1
			type_bottom_field=1
		]
		timing_info=[
			num_units_in_tick=1
			time_scale=61
			fixed_frame_rate_flag=1
		]
		nal_hrd_parameters=[
			<Not present>
		]
		vcl_hrd_parameters=[
			<Not present>
		]
		pic_struct_present_flag=1
		bitstream_restriction=[
			motion_vectors_over_pic_boundaries_flag=1
			max_bytes_per_pic_denom=0
			max_bits_per_mb_denom=0
			log2_max_mv_length_horizontal=10
			log2_max_mv_length_vertical=10
			max_num_reorder_frames=0
			max_dec_frame_buffering=3
		]
	]
	separate_colour_plane_flag=0
[/H264SeqParameterSet]

For some reason time_scale says 61 rather than 60. I'll investigate later.

[mildsunrise]

(rebased)

[murillo128]

is this ready for review?

[mildsunrise]

it is missing a relatively small change for it to compile without RTTI. sorry, I'll push that change tomorrow.
for all other intents and purposes, this can be considered ready to review yes