fix: when using module-dirs from project, make dirs absolute

[wesbillman]

I noticed an issue where the LSP was not clearing the diagnostics correctly for modules when rebuilding.

It turned out that the module.Dir was only relative when loaded from the project toml vs. absolute when used with "." or ftl dev example/go. This change makes sure we set the absolute paths on the config.ModuleDirs and config.ExternalDirs when loading them from ftl-project.toml files.

Before this change the lsp would try to clear files with the following path. This would result in LSP errors never being cleared.

lsp: Clearing diagnostics for file:///examples/go/echo

This update, ensures that path is absolute

lsp: Clearing diagnostics for file:///Users/wesbillman/dev/ftl/examples/go/echo

[alecthomas]

@wesbillman I had to revert this because it was writing absolute paths back into the config file, so we'll need to come up with an alternate fix.

diff --git a/ftl-project.toml b/ftl-project.toml
index fd63b39f..7e2ba264 100644
--- a/ftl-project.toml
+++ b/ftl-project.toml
@@ -1,10 +1,11 @@
-module-dirs = ["examples/go"]
+module-dirs = ["/Users/alec/dev/ftl/examples/go"]
 external-dirs = []
 ftl-min-version = ""
 
 [global]