clp-core: Replace calls to incomplete UTF-8 validation function with new and complete implementation.

[LinZhihao-723]

Description

This PR:

1. Replace the UTF-8 buffer validation with dedicated methods introduced in PR Add support for validating and escaping UTF-8 strings. #453
2. Remove UTF-8 validation helpers in the current clp/utils as it doesn't validate UTF-8 code point ranges.

Validation performed

1. Add three files into a directory: one valid raw log file, one valid zstd compressed IR file, and clp binary. Compress the archive using clp and ensure raw log and IR can be properly compressed, but not clp binary.
2. Repeat step 1 by first compressing the directory using zip to trigger libarchive reading path. Ensure the raw log can be properly compressed (but not IR, since libarchive reader will not recursively decompress the zstd compressed IR stream)
3. Ensure workflow passed

[haiqi96]

It's a simple change and looks good to me

[kirkrodrigues]

For the PR title, how about:

clp-core: Replace calls to incomplete UTF-8 validation function with new and complete implementation.

[LinZhihao-723]

For the PR title, how about:

clp-core: Replace calls to incomplete UTF-8 validation function with new and complete implementation.

LGTM