fix: pad base64 strings for base64js

[alexander-fenster]

Fixes #716. Also, adding tests for both crypto implementations.

• Tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

[codecov]

Codecov Report

Merging #722 into master will decrease coverage by 0.09%.
The diff coverage is 0%.

@@            Coverage Diff            @@
##           master     #722     +/-   ##
=========================================
- Coverage   84.78%   84.69%   -0.1%     
=========================================
  Files          18       18             
  Lines         940      941      +1     
  Branches      209      209             
=========================================
  Hits          797      797             
- Misses         83       84      +1     
  Partials       60       60

Impacted Files	Coverage Δ
src/crypto/crypto.ts	71.42% <ø> (ø)	⬆️
src/crypto/browser/crypto.ts	10% <0%> (-0.35%)	⬇️

---

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[codecov]

Codecov Report

Merging #722 into master will decrease coverage by 0.09%.
The diff coverage is 0%.

@@            Coverage Diff            @@
##           master     #722     +/-   ##
=========================================
- Coverage   84.78%   84.69%   -0.1%     
=========================================
  Files          18       18             
  Lines         940      941      +1     
  Branches      209      209             
=========================================
  Hits          797      797             
- Misses         83       84      +1     
  Partials       60       60

Impacted Files	Coverage Δ
src/crypto/crypto.ts	71.42% <ø> (ø)	⬆️
src/crypto/browser/crypto.ts	10% <0%> (-0.35%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e53acfb...5759fdb. Read the comment docs.