feat: add tag-suffix and tag-prefix options

[CharlieC3]

Adds tag-prefix and tag-suffix options.

• tag-prefix will prepend the given string to the beginning of all Docker tags
  • e.g. If tag-prefix given is prepend-, my/app:dev becomes my/app:prepend-dev
• tag-suffix will append the given string to the end of all Docker tags
  • e.g. If tag-suffix given is -append, my/app:dev becomes my/app:dev-append
• Both options can be used simultaneously
• Added new tests
• All tests passing
• Followed contribution guidelines

Addresses #13

[codecov]

Codecov Report

Merging #47 (dcdcc82) into master (5f29dbc) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master      #47   +/-   ##
=======================================
  Coverage   75.42%   75.42%           
=======================================
  Files           3        3           
  Lines         118      118           
  Branches       24       24           
=======================================
  Hits           89       89           
  Misses          7        7           
  Partials       22       22           

Impacted Files	Coverage Δ
src/context.ts	85.71% <ø> (ø)
src/meta.ts	76.54% <100.00%> (ø)

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[crazy-max]

@CharlieC3 Thanks for your contrib but like I said in #15 (comment), I will focus on proposal in #30. I keep this one open in the meantime. Keep you in touch.