Clean, unify code and standardize code

[nhhaidee]

• Clean and reformat code
• Unify code between components
• Use eslint to check js code
• Other updates:
  • https://github.com/nhhaidee/wgscovplot/issues/26: tool automatically retrieves and parses reference sequence, gene feature (support both GFF and genbank)
  • Some updates and fixes for https://github.com/nhhaidee/wgscovplot/issues/3
  • Updates for issues: https://github.com/nhhaidee/wgscovplot/issues/28
  • Fix issue https://github.com/nhhaidee/wgscovplot/issues/36, https://github.com/apache/echarts/issues/17657

• General data structure:

  Segment virus:
  
  samples = ["Sample01", "Sample02", "Sample03"]
  segments = ["1_PB2", "2_PB1", "3_PA", "4_HA",  "5_NP", "7_M", "8_NS"]
  depths: { 'SAMPLE_NAME':{
               'SEGMENT_NAME': [] // array
           }
       }
  variants: { 'SAMPLE_NAME':{
             'SEGMENT_NAME': {}
           }
       }
  refSeq: { 'SAMPLE_NAME':{
             'SEGMENT_NAME': ref_seq (str)
           }
       }
  refID: { 'SAMPLE_NAME':{
             'SEGMENT_NAME': ref_id (str)
           }
       }
  primerData: { 'SAMPLE_NAME':{
             'SEGMENT_NAME': {}
           }
       }
  
  Non-segment virus:
  
  samples = ["Sample01", "Sample02", "Sample03"]
  geneFeatureAmpliconData = [{ // use to plot gene feature and amplicon
                 "idx": index,
                 "start": start_pos,
                 "end": end_pos,
                 "level": level,
                 "strand": strand,
                 "type": "gene_feature or amplicon"}]
  ampliconDepthBarData = [{  // used to plot amplicon bar together with coverage depth chart
                 "value": [start, end, depth, name]
                 "itemStyle": {"color": "skyblue or violet"}}]
  depths = [
    [1, 2, 45, 3, 2, 34, 54, 65, 7, 6, 34, 45, 56, 67, 78, 78],
    [1, 2, 45, 0, 0, 9, 15, 65, 7, 6, 20, 8, 4, 15, 100, 102],
    [12, 12, 425, 3, 2, 10, 12, 9, 7, 6, 1, 45, 45, 67, 87, 97]
  ] // same sample index order as in samples array 
  variants = [
    [0:{sample: 'sample1', CHROM: 'MN908947.3',mutation: 'C14408T(orf1ab:L4715L)',POS: 14408},
     1:{sample: 'sample1', CHROM: 'MN908947.3',mutation: 'C14408T(orf1ab:L4715L)',POS: 29300}],
    [0:{sample: 'sample2', CHROM: 'MN908947.3',mutation: 'C15480A(orf1ab:P5072H)',POS: 10000},
     1:{sample: 'sample2', CHROM: 'MN908947.3',mutation: 'C15480A(orf1ab:P5072H)',POS: 25300}]
  ] // same sample index order as in samples array