Libva-utils 2.18.1

• doc:Add build and install libva-utils steps
• test: Add VAProfileH264High10
• test: Don't assume our DRM node is first
• add: va_display_drm: Allow VGEM for WSL2
• win: win32 compat: Fix setenv/unsetenv return values
• fix: Add Th limitation by HUFFMAN_TABLES Count
• fix: Add refresh_frame_flags in PPS
• fix: Add checking of stream_scan size
• fix: Add Scan Num limitation
• fix: Changed H2S configuration template.
• fix: Correct maximum display luminance per VAAPI definition.
• fix: Fix possible memory leak
• fix: Fix coding issues of function return type & ref_frame_idx idx too large