fix(core): use loadFile instead of loadURL in the default template

[malept]

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• The changes have sufficient test coverage (if applicable).
• The testsuite passes successfully on my local machine (if applicable).

Summarize your changes:

Fixes #1339.

[codecov]

Codecov Report

Merging #1341 into master will decrease coverage by 24.9%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master    #1341       +/-   ##
===========================================
- Coverage   66.43%   41.53%   -24.91%     
===========================================
  Files          70        4       -66     
  Lines        2038      183     -1855     
  Branches      382       37      -345     
===========================================
- Hits         1354       76     -1278     
+ Misses        533       95      -438     
+ Partials      151       12      -139

Impacted Files	Coverage Δ
packages/api/core/src/api/import.ts	26% <0%> (-32.42%)	⬇️
packages/maker/snap/src/MakerSnap.ts
...es/api/core/src/api/init-scripts/init-directory.ts
packages/api/core/src/util/index.ts
packages/api/core/src/util/publish-state.ts
packages/utils/async-ora/src/index.ts
packages/maker/wix/src/util/author-name.ts
packages/plugin/webpack/src/WebpackPlugin.ts
packages/maker/rpm/src/MakerRpm.ts
packages/installer/base/src/Installer.ts
... and 56 more

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