Be defensive when passing potentially nil strings to Gem::Version

(cherry picked from commit 04cbea4d)

Fix compatibility with RubyGems v2.7.7

Done by using Pod::Version instead of Gem::Version, which in 2.7.7 stop allowing initializing a version with `nil`

Do not include test dependencies input and output paths

(cherry picked from commit 781d5047)

# Conflicts:
#	spec/unit/installer/xcode/pods_project_generator/pod_target_integrator_spec.rb

Change generated asset catalog plist name

(cherry picked from commit c109b144)

# Conflicts:
#	spec/cocoapods-integration-specs

Do not force `[system]` value for custom module maps

(cherry picked from commit 644280b5)

# Conflicts:
#	spec/cocoapods-integration-specs

Remove [system] declaration attribute from generated module maps

(cherry picked from commit 0a93634a)

# Conflicts:
#	spec/cocoapods-integration-specs

Make modular header private header access consistent

(cherry picked from commit 56231f98)

# Conflicts:
#	spec/cocoapods-integration-specs

Fix assetcatalog_generated_info.plist path in copy resources phase

(cherry picked from commit 76c47a81)

# Conflicts:
#	spec/cocoapods-integration-specs

Prevent duplicated targets from being stripped out from the framework search paths

(cherry picked from commit 15df291f)

Always generate FRAMEWORK_SEARCH_PATHS for vendored_frameworks

(cherry picked from commit d4468d5b)

Fix static framework dependent target double linking 

(cherry picked from commit 8e0f3b09)

Fix modular header access to header_dirs

(cherry picked from commit 4d95ed04)

Use `flat_map` instead of flatten in some cases

Return list of files preserving given pattern order on glob

fix pod lib lint errors for pod with test_spec

Mixed language static frameworks

Update validator to stream output as xcodebuild runs

Updated validator's xcodebuild command to stream output as it runs, instead of holding it until the end, when given the --verbose flag (issue #7040)