refactor: remove temp page files and load page component via bundler (close #1584)

[meteorlxy]

Before submitting the PR, please make sure you do the following

• [x] Read the Contributing Guidelines.
• [x] Provide a description in this PR that addresses what the PR is solving. If this PR is going to solve an existing issue, please reference the issue (e.g. close #123).

What is the purpose of this pull request?

• [ ] Bug fix
• [ ] New feature
• [ ] Documentation update
• [ ] Other
• [x] Refactor

Description

Closes #1584

Changes:

• refactor: remove temp page files and load page component via bundler
• refactor(markdown): remove relativePathPrefix option from assetsPlugin
• feat: support importing module via relative paths in page files
• feat: support importing markdown as vue component

TODOs

• ~HMR~
• Refactor dev watcher, update pages & pagesMap
• Watch page deps and invalidate the cache

[coveralls]

Pull Request Test Coverage Report for Build 16794974048

Details

• 36 of 59 (61.02%) changed or added relevant lines in 13 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.2%) to 73.229%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/cli/src/commands/dev/handlePageUnlink.ts	0	1	0.0%
packages/core/src/app/appPrepare.ts	0	1	0.0%
packages/cli/src/commands/dev/handlePageAdd.ts	0	2	0.0%
packages/cli/src/commands/dev/handlePageChange.ts	0	2	0.0%
packages/core/src/app/prepare/preparePageChunk.ts	0	2	0.0%
packages/core/src/page/renderPageToVue.ts	19	34	55.88%
<!--	Total:	36	59

Totals
Change from base Build 16794961355:	-1.2%
Covered Lines:	698
Relevant Lines:	945

---

💛 - Coveralls