Improve stack var type detection

[frmdstryr]

Is your feature request related to a problem? Please describe.

The type of some stack variables types could possibly be improved.

Describe the solution you'd like

It may be possible to detect based on move instructions. For instance var_ch can is used with a mov byte instruction but is detected as an int64_t.

Describe alternatives you've considered A clear and concise description of any alternative solutions or features you've considered.

Additional context

For example in the main function of the test bin at bins/elf/struct64

Blocked on https://github.com/rizinorg/rizin/issues/2080 just like https://github.com/rizinorg/rizin/issues/1256