feat(ThemeProvider)!: restructure default component theme

[arpitBhalla]

import { createTheme } from '@rneui/themed';

const myTheme = createTheme({
+  components: {
    Button:{
      titleStyle: {
        color: 'red'
      },
    },
+  },
});

[codecov]

Codecov Report

Merging #3582 (2ae3373) into next (182861e) will decrease coverage by 0.23%.
The diff coverage is 87.50%.

@@            Coverage Diff             @@
##             next    #3582      +/-   ##
==========================================
- Coverage   79.61%   79.38%   -0.24%     
==========================================
  Files          87       87              
  Lines        1805     1809       +4     
  Branches      799      801       +2     
==========================================
- Hits         1437     1436       -1     
- Misses        362      367       +5     
  Partials        6        6              

Impacted Files	Coverage Δ
packages/themed/src/config/withTheme.tsx	86.48% <75.00%> (+0.37%)	⬆️
packages/themed/src/config/ThemeProvider.tsx	65.95% <100.00%> (-9.05%)	⬇️

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