FASTA: Kindly add warning about lost some information while we save mix of DNA and RNA nucleotides to one FASTA file.

[NadezhdaPeskun]

Steps to Reproduce

1. Switch to Macro
2. Open >> Paste from clipboard >> Add "> AAATTT" >> Select 'FASTA' >> select RNA >> Add to Canvas

3.Open >> Paste from clipboard >> Add "> AAATTT" >> Select 'FASTA' >> select DNA >> Add to Canvas
4. We have mix RNA and DNA

5. Save in FASTA >>AAATTTAAATTT are saved

Actual behavior
Save in FASTA, RNA and DNA mixture is lost (AAATTTAAATTT are saved) and we can open all symbols only as RNA or as DNA.

Expected behavior
Kindly add warning about lost some information while we save as mix of DNA and RNA nucleotides to FASTA.
As per requirements
In case of multiple types sequences on canvas, error "Error during sequence type recognition(RNA, DNA or Peptide)" should appear

• Macro: UI for Open/Save As FASTA #4146
• Autotests: Macro: UI for Open/Save As FASTA/Sequence #4280

Versions:
OS: Windows 10
Browser Chrome
Version 112.0.5615.138 (Official Build) (64-bit)

Version 2.20.0-rc.1
Build at 2024-03-15; 15:36:45
Indigo Toolkit
Version 1.19.0-rc.1.0-g8cd9f1e27-wasm32-wasm-clang-12.0.0