feat: support saving markdown report to a file

[LinuxSuRen]

fix #73

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[codacy-production]

Coverage summary from Codacy

Merging #74 (60e2a1d) into master (54b1194) - See PR on Codacy

Coverage variation	Diff coverage
+0.04%	100.00%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (54b1194)	1213	1131	93.24%
Head commit (60e2a1d)	1220 (+7)	1138 (+7)	93.28% (+0.04%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#74)	8	8	100.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

See your quality gate settings    Change summary preferences