rename unclear *run* methods to *install_extension* + rename install_extensions to install_all_extensions

[lexming]

fixes #4113

• run() -> install_extension()
• prerun() -> pre_install_extension()
• postrun() -> post_install_extension()
• run_async() -> install_extension_async()
• install_extensions() -> install_all_extensions()

[lexming]

@boegel I made your suggested changes

[boegel]

@lexming We need a companion PR in easyblocks too?

[boegel]

Companion easyblocks PR:

• rename run method to install_extension, and likewise for prerun to pre_install_extension, postrun to post_install_extension, and run_async to install_extension_async easybuild-easyblocks#3064

[lexming]

@boegel all tests positive, this is ready

[lexming]

@boegel added unit tests for the new method Extension.install_extension_substep. I had to add various new easyblocks to the test sandbox to be able to test the case where some easyblock inherits custom or deprecated run methods from a parent class. So there are collateral changes due to those additions.

If you think that adding those extra easyblocks is overkill, we can also just test the case where an easyblock directly defines custom or deprecated run methods. For such cases, the DummyExtension easyblock is sufficient.

Regarding the use of __qualname__, the qualified name is indeed also printed as part of the string representation of the method. However, that requires parsing something like <bound method XXXX.xxx of XXX object at 0x000000000000>, which IMO is more prone to error than handling __qualname__. So I left that part unchanged.

[boegel]

lgtm