Added a theme provider

[matheusps]

solves #12

[codecov-io]

Codecov Report

Merging #13 into master will increase coverage by 0.78%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #13      +/-   ##
==========================================
+ Coverage   96.77%   97.56%   +0.78%     
==========================================
  Files           5        7       +2     
  Lines          31       41      +10     
  Branches       10       11       +1     
==========================================
+ Hits           30       40      +10     
  Misses          1        1

Impacted Files	Coverage Δ
src/components/Loader/helpers/styled.ts	100% <100%> (ø)
src/components/Loader/index.tsx	100% <100%> (ø)	⬆️
src/components/StellarTheme/index.tsx	100% <100%> (ø)
src/components/StellarTheme/stockThemes.ts	100% <100%> (ø)

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