feat: basic template imports support (<template> tag and gts, gjs files)

[lifeart]

In scope of this PR i'm planning to land list of primitives to work with mixed content (multiple langs in one file)

To do:

• add integration test with gjs file
• add integration test with gts file
• add linting support to gjs file

#349

[codecov]

Codecov Report

Merging #350 (c9cdd7e) into component-context-info-origin (ef13b60) will increase coverage by 0.53%.
The diff coverage is 79.77%.

@@                        Coverage Diff                        @@
##           component-context-info-origin     #350      +/-   ##
=================================================================
+ Coverage                          71.10%   71.63%   +0.53%     
=================================================================
  Files                                 49       53       +4     
  Lines                               4101     4400     +299     
  Branches                             801      838      +37     
=================================================================
+ Hits                                2916     3152     +236     
- Misses                              1182     1245      +63     
  Partials                               3        3              

Impacted Files	Coverage Δ
src/builtin-addons/core/code-actions/base.ts	20.37% <25.00%> (-0.56%)	⬇️
src/definition-providers/glimmer-script.ts	25.80% <25.80%> (ø)
src/definition-providers/entry.ts	75.86% <50.00%> (-3.31%)	⬇️
...ion-provider/glimmer-script-completion-provider.ts	84.09% <84.09%> (ø)
src/utils/glimmer-script.ts	85.08% <85.08%> (ø)
...ompletion-provider/template-completion-provider.ts	88.57% <91.30%> (-4.70%)	⬇️
src/utils/glimmer-template.ts	94.00% <94.00%> (ø)
.../completion-provider/script-completion-provider.ts	78.72% <100.00%> (+1.97%)	⬆️
src/template-linter.ts	46.66% <100.00%> (+2.91%)	⬆️
src/utils/layout-helpers.ts	92.23% <100.00%> (ø)
... and 4 more

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