feat(intl): implement Currency#fromString to parse currency strings

[faustbrian]

Implements a way to parse currency strings to get the raw numbers from it. Requires to pass in a magnitude to limit the decimal numbers but defaults to 8 for the magnitude.

[codecov]

Codecov Report

Merging #438 into master will increase coverage by 4.88%.
The diff coverage is 71.73%.

@@            Coverage Diff             @@
##           master     #438      +/-   ##
==========================================
+ Coverage   66.66%   71.55%   +4.88%     
==========================================
  Files          45       49       +4     
  Lines         735      928     +193     
  Branches       46       65      +19     
==========================================
+ Hits          490      664     +174     
- Misses        228      240      +12     
- Partials       17       24       +7     

Flag	Coverage Δ
#unit	71.55% <71.73%> (+4.88%)	⬆️

Impacted Files	Coverage Δ
packages/platform-sdk-intl/src/currency.ts	71.73% <71.73%> (ø)
packages/platform-sdk-intl/src/datetime.ts	95.53% <0.00%> (ø)
packages/platform-sdk-intl/src/money.ts	96.15% <0.00%> (ø)
packages/platform-sdk-intl/src/numeral.ts	100.00% <0.00%> (ø)

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