perf: avoid unnecessary byte/string conversion

[Juneezee]

PR Details

We can use alternative functions/methods to avoid unnecessary byte/string conversion calls.

Description

1. (*Builder).WriteString(string(<a byte>)) -> (*Builder).WriteByte(<a byte>)
2. (*Regexp).Match([]byte(<a string>)) -> (*Regexp).MatchString(<a string>)

Related Issue

Motivation and Context

How Has This Been Tested

go test ./...
ok  	github.com/xuri/excelize/v2	63.499s

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov-commenter]

Codecov Report

Merging #1541 (f0b8454) into master (a246db6) will not change coverage.
The diff coverage is 100.00%.

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@@           Coverage Diff           @@
##           master    #1541   +/-   ##
=======================================
  Coverage   98.82%   98.82%           
=======================================
  Files          31       31           
  Lines       24494    24494           
=======================================
  Hits        24206    24206           
  Misses        191      191           
  Partials       97       97           

Flag	Coverage Δ
unittests	98.82% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
numfmt.go	100.00% <100.00%> (ø)
table.go	99.15% <100.00%> (ø)

[xuri]

LGTM. Thank you very much.