ISSUE #11300: Improve Routing Syntax Import Error

modified FileLoaderLoadException message to present the previous (Parse)Exception first
Add test and small code fix
Addition of the symfony license text
- Removed spaces around the concation dots to be more consitent
- adjusted some formatting
Merge remote-tracking branch 'upstream/master'
removed some more spaces
feature #11313 [Config][Exception] Improve Routing Syntax Import Error (Jan Decavele, tvlooy)

This PR was merged into the 2.6-dev branch.

Discussion
----------

[Config][Exception] Improve Routing Syntax Import Error

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11300
| License       | MIT
| Doc PR        | n/a

Commits
-------

fec9a4a removed some more spaces
16134d9 Merge remote-tracking branch 'upstream/master'
b099936 - Removed spaces around the concation dots to be more consitent - adjusted some formatting
0459d89 Addition of the symfony license text
de43182 Add test and small code fix
8ac5275 ISSUE #11300: Improve Routing Syntax Import Error