CharsetObjectCanBeUsedInspection: suggest replacing Charset.forName(XYZ) with StandardCharsets.XYZ (IDEA-210209)

build scripts: provide common option to enable injection of URL of custom plugins repository to ApplicationInfo.xml

Replace 'intellij.build.prepare.plugin.repository' system property which is used in IDEA only by the common 'intellij.build.use.teamcity.as.plugins.repository' property so we can enable builtin plugin repository in nightly build of other IDEs as well. Also the new property enables only adding reference to TeamCity artifacts into the product, the custom repository xml file is always generated in TeamCity artifacts so it can be used manually even for public builds.

IDEA project configuration: enable inspection about access to package-private members from different module

This is needed to avoid such code because it'll lead to IllegalAccessError if e.g. Java support code is loaded as a plugin via a different classloader (see IDEA-200277). Modules belonging to same plugins are listed in the inspection settings and accessing package-private member between classes from them aren't reported.

There are some false-positives because of bugs in the inspection (see IDEA-210216, IDEA-210253), they are temporarily suppressed.

IDEA-210298 Result of method call ignored false-positive on Validate.nonNull check from commons-lang3

Provide better painting and scrolling for editor tabs, allow to make selected tab temporary invisible while user scrolls

- the last entry is removed

merging "Multiple variables in one declaration" and "Multiple typed variables in one declaration" inspections