resolve path when registering watcher for module paths

[zyxue]

Describe your changes

I am developing a streamlit app in Bazel, which creates many symlinks when building a project, e.g.

bazel-bin/projects/myapp/pages/0_Overview.py => foo/projects/myapp/pages/0_Overview.py
bazel-bin/projects/myapp/utils.py => => foo/projects/myapp/utils.py

I usually edit files in foo/ during development, and I found that when updating module file (utils.py), the change is not detected by streamlit and the browser does not refresh, automatically. However, updating the page file (e.g. 0_Overview.py) would lead to auto refresh. Then, after debugging, I think it's due to the inconsistency in resolutions of page and module paths.

Specifically, when streamlit is run and registering watchers, only the paths of page files get resolved (make absolute path and resolve symlink), the relevant code snippets are

streamlit/lib/streamlit/watcher/local_sources_watcher.py

Lines 54 to 58 in 4589b13

	for page_info in get_pages(self._main_script_path).values():
	self._register_watcher(
	page_info["script_path"],
	module_name=None, # Only root scripts have their modules set to None
	)

streamlit/lib/streamlit/source_util.py

Line 132 in 4589b13

"script_path": str(main_script_path.resolve()),

streamlit/lib/streamlit/source_util.py

Line 147 in 4589b13

script_path_str = str(script_path.resolve())

However, the module paths don't get resolved

streamlit/lib/streamlit/watcher/local_sources_watcher.py

Line 150 in 4589b13

self._register_watcher(path, name)

which explains the inconsistent auto refresh behavior and is what this PR updates. In essence, we only want to watch the change in the resolved paths, the content of the symlink path, which just holds a link to the source file, does not change.

GitHub Issue Link (if applicable)

Testing Plan

manually tested it's working.

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[vdonato]

LGTM -- thanks for the contribution @zyxue!