utf8 and general checklist

[matu3ba]

1. [ ] formulate assumptions for linebreak characters on OSes
2. [ ] create CI
3. [ ] automate benchmarks in build.zig

Incomplete list to check for utf8

• [ ] slow path as another cli flag for validating correct utf8, TODO: check zigstr examples etc
• [x] use std.unicode to interpret the bits as utf8 (for perf reasons)
• [x] use jump tag with state machine for parsing all paths
• [ ] control characters, TODO: check utf8 cntrl chars
• [x] forbid whitespaces except the simple one
• [x] forbid prefixed dashes
• [x] forbid prefixed and postfixed whitespace
• [ ] apply the utf8 checks to shell+file output with correct return codes/error handling.

Other perf improvements:

• [ ] use buffered output (rather simple)
• [ ] use buffer-backed allocator instead of allocating space (move stuff into library file)
• [ ] comptime-construct string message offsets for printing (stage2)
• [ ] optimize len fields (tedious)

[matu3ba]

zigstr provides printing/rendering support and meta information. std.unicode only provides the unicode codepoints, which need to be combined to get aforementioned information.